Won-Jea Cho

Metformin Inhibits Hepatic Gluconeogenesis Through AMP-Activated Protein Kinase–Dependent Regulation of the Orphan Nuclear Receptor SHP

OBJECTIVE—Metformin is an antidiabetic drug commonly used to treat type 2 diabetes. The aim of the study was to determine whether metformin regulates hepatic gluconeogenesis through the orphan nuclear receptor small heterodimer partner (SHP; NR0B2). RESEARCH DESIGN AND METHODS—We assessed the regulation of hepatic SHP gene expression by Northern blot analysis with metformin and adenovirus containing a constitutive active form of AMP-activated protein kinase (AMPK) (Ad-AMPK) and evaluated SHP, PEPCK, and G6Pase promoter activities via transient transfection assays in hepatocytes. Knockdown of SHP using siRNA SHP was conducted to characterize the metformin-induced inhibition of hepatic gluconeogenic gene expression in hepatocytes, and metformin–and adenovirus SHP (Ad-SHP)–mediated hepatic glucose production was measured in B6-Lepob/ob mice. RESULTS—Hepatic SHP gene expression was induced by metformin, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), and Ad-AMPK. Metformin-induced SHP gene expression was abolished by adenovirus containing the dominant negative form of AMPK (Ad-DN-AMPK), as well as by compound C. Metformin inhibited hepatocyte nuclear factor-4α–or FoxA2-mediated promoter activity of PEPCK and G6Pase, and the inhibition was blocked with siRNA SHP. Additionally, SHP knockdown by adenovirus containing siRNA SHP inhibited metformin-mediated repression of cAMP/dexamethasone-induced hepatic gluconeogenic gene expression. Furthermore, oral administration of metformin increased SHP mRNA levels in B6-Lepob/ob mice. Overexpression of SHP by Ad-SHP decreased blood glucose levels and hepatic gluconeogenic gene expression in B6-Lepob/ob mice. CONCLUSIONS—We have concluded that metformin inhibits hepatic gluconeogenesis through AMPK-dependent regulation of SHP.

Orphan Nuclear Receptor Estrogen-Related Receptor γ (ERRγ) Is Key Regulator of Hepatic Gluconeogenesis

Background: Dysregulation of glucose homeostasis is often associated with insulin resistance and diabetes. Results: Hepatic ERRγ expression is increased by fasting-dependent activation of the CREB-CRTC2 pathway, which leads to the induction of hepatic gluconeogenesis. Conclusion: Orphan nuclear receptor ERRγ is a novel transcriptional regulator of hepatic gluconeogenesis. Significance: An ERRγ inverse agonist could be a new potential therapeutic approach for the treatment of type 2 diabetes. Glucose homeostasis is tightly controlled by hormonal regulation of hepatic glucose production. Dysregulation of this system is often associated with insulin resistance and diabetes, resulting in hyperglycemia in mammals. Here, we show that the orphan nuclear receptor estrogen-related receptor γ (ERRγ) is a novel downstream mediator of glucagon action in hepatic gluconeogenesis and demonstrate a beneficial impact of the inverse agonist GSK5182. Hepatic ERRγ expression was increased by fasting-dependent activation of the cAMP-response element-binding protein-CRTC2 pathway. Overexpression of ERRγ induced Pck1 and G6PC gene expression and glucose production in primary hepatocytes, whereas abolition of ERRγ gene expression attenuated forskolin-mediated induction of gluconeogenic gene expression. Deletion and mutation analyses of the Pck1 promoter showed that ERRγ directly regulates the Pck1 gene transcription via ERR response elements of the Pck1 promoter as confirmed by ChIP assay and in vivo imaging analysis. We also demonstrate that GSK5182, an inverse agonist of ERRγ, specifically inhibits the transcriptional activity of ERRγ in a PGC-1α dependent manner. Finally, the ERRγ inverse agonist ameliorated hyperglycemia through inhibition of hepatic gluconeogenesis in db/db mice. Control of hepatic glucose production by an ERRγ-specific inverse agonist is a new potential therapeutic approach for the treatment of type 2 diabetes.

Prediction of the binding mode of imidacloprid and related compounds to house-fly head acetylcholine receptors using three-dimensional QSAR analysis

The binding activity of imidacloprid and related compounds to nico- tinic acetylcholine receptors (nAChR) of house Nies was measured by use of radioactive a-bungarotoxin as a ligand. Variations in the activity were examined three-dimensionally using comparative molecular -eld analysis (CoMFA). The CoMFA results suggest that one conformer among the four stable ones is active and provide support for one of the proposed binding models for this class of compound, in which the nitrogen atom of the pyridine ring and the nitrogen atom at the 1-position of the imidazolidine ring interact with the hydrogen- donating and electron-rich sites of nAChR, respectively. The CoMFA -eld map showed that the nitroimino moiety and a portion of the imidazolidine ring were mainly surrounded by a sterically and electrostatically sensitive region of nAChR. 1998 Society of Chemical Industry ( Pestic. Sci., 54, 134E144 (1998)

Akt Cys-310-targeted Inhibition by Hydroxylated Benzene Derivatives Is Tightly Linked to Their Immunosuppressive Effects

The hydroxylated benzene metabolite hydroquinone (HQ) is mainly generated from benzene, an important industrial chemical, and is also a common dietary component. Although numerous reports have addressed the tumorigenesis-inducing effects of HQ, few papers have explored its molecular regulatory mechanism in immunological responses. In this study we characterized Akt (protein kinase B)-targeted regulation by HQ and its derivatives, in suppressing inflammatory responses using cellular, molecular, biochemical, and immunopharmacological approaches. HQ down-regulated inflammatory responses such as NO production, surface levels of pattern recognition receptors, and cytokine gene expression with IC50 values that ranged from 5 to 10 μm. HQ inhibition was mediated by blocking NF-κB activation via suppression of its translocation pathway, which is composed of Akt, IκBα kinase β, and IκBα. Of the targets in this pathway, HQ directly targeted and bound to the sulfhydryl group of Cys-310 of Akt and sequentially interrupted the phosphorylation of both Thr-308 and Ser-473 by mediation of β-mercaptoethanol, according to the liquid chromatography/mass spectroscopy analysis of the interaction of HQ with an Akt-derived peptide. Therefore, our data suggest that Akt and its target site Cys-310 can be considered as a prime molecular target of HQ-mediated immunosuppression and for novel anti-Akt-targeted immunosuppressive drugs.

Synthesis and biological evaluation of 3-arylisoquinolines as antitumor agents

To investigate the structure-activity relationship of 7,8-dimethoxy-2- methyl-3-(4,5-methylenedioxy-2-vinylphenyl)isoquinolin-1(2H) -one 2, diverse substituted 3-arylisoquinolines were synthesized and tested in vitro antitumor activity against five human tumor cell lines. The results showed a broad antitumor spectrum for a series of 3-arylisoquinolines.

Molecular modeling of 3-arylisoquinoline antitumor agents active against A-549. A comparative molecular field analysis study

A series of 58 3-arylisoquinoline antitumor agents were investigated for defining the pharmacophore model using comparative molecular field analysis (CoMFA) program. The studied compounds related to bioisostere of benzophenanthridine alkaloid were synthesized and evaluated for antitumor cytotoxicity against human lung tumor cell (A 549). In order to perform the systematic molecular modeling study of these compounds, the conformational search was carried out based on the single X-ray crystallographic structure of 7,8-dimethoxy-3-phenylisoquinolin-(2H)-one (2). Interestingly, two types of structures having different dihedral angles between the isoquinoline ring and 3-aryl ring were found in the crystals. Therefore, CoMFA was performed two different, overlapping ways. The alignments of the structures were based on the common isoquinoline ring and 3-aryl ring. The 3-D-quantitative structure-activity relationship study resulted in significant cross-validated, conventional r(2) values equal to 0.715 and 0.927, respectively.

Dihydroxylated 2,4,6-triphenyl pyridines: Synthesis, topoisomerase I and II inhibitory activity, cytotoxicity, and structure—activity relationship study

Twelve dihydroxylated 2,4,6-triphenyl pyridines were designed and synthesized which contain hydroxyl groups at ortho, meta or para position of 2- and 6-phenyl, or 2- and 4-phenyl rings attached to the central pyridine. They were evaluated for topoisomerase I and II inhibitory activity, and cytotoxicity against several human cancer cell lines for the development of novel anticancer agents. Generally, dihydroxylated 2,4,6-triphenyl pyridines exhibited stronger topoisomerase II inhibitory activity, and cytotoxicity compared to those of monohydroxylated 2,4,6-triphenyl pyridines. The concrete structure-activity relationship was observed that dihydroxylated 2,4,6-triphenyl pyridines with hydroxyl group at meta or para position of 2-phenyl ring displayed significant topoisomerase II inhibitory activity as well as cytotoxicity. Positive correlation between topoisomerase II inhibitory activity and cytotoxicity was observed for compounds 10, 12, 13, 17-20 and 22.

Molecular design, synthesis and docking study of benz[b]oxepines and 12-oxobenzo[c]phenanthridinones as topoisomerase 1 inhibitors.

Benz[b]oxepines 4a-g and 12-oxobenzo[c]phenanthridines 5a-d were designed and synthesized as constrained forms of 3-arylisoquinolines through an intramolecular radical cyclization reaction. Radical cyclization of O-vinyl compounds preferentially led to the 7-endo-trig cyclization pathway to the benz[b]oxepines and 12-oxobenzo[c]phenanthridines through 6-exo-trig path as minor products. Among the synthesized compounds, benz[b]oxepine derivative 4e exhibited potent in vitro cytotoxicity against three different tumor cell lines, as well as topoisomerase 1 inhibitory activity. A Surflex-Dock docking study was performed to clarify the topoisomerase 1 activity of 4e.

Structural modification of 3-arylisoquinolines to isoindolo[2,1-b]isoquinolinones for the development of novel topoisomerase 1 inhibitors with molecular docking study

Isoindolo[2,1-b]isoquinolinones 9a-i were designed and synthesized as constrained forms of 3-arylisoquinolines through an intramolecular cyclization reaction. Among the synthesized compounds, 9d exhibited potent topoisomerase 1 inhibitory activity with cytotoxicities against three different tumor cell lines. A Surflex-dock docking study was performed to clarify the topoisomerase 1 inhibitory activity of 9d.

Topoisomerase inhibitors as anticancer agents: a patent update

Introduction: Topoisomerases (topos) are nuclear enzymes that resolve topological problems associated with DNA during various genetic processes. The essential role of topos in vital processes of the cell, their elevated level in solid tumors and cell death due to their inhibition make topos inhibitors as a potent class of antineoplastic agents. Areas covered: This review specifically summarizes patents embracing topo I, topo I and II inhibitors. The review covers topos inhibitors which are structurally close to camptothecin (CPT), natural products such as lamellarins and synthetic trisubstituted pyridines. It largely focuses on chemical entities developed by systematic structure–activity relationship (SAR) studies of natural benzo[c]phenanthridine (nitidine) and synthetic protoberberine (coralyne) established as antineoplastic agents targeting topo(s). In addition, indenoisoquinolines and evodiamines initially discovered through COMPARE analysis and receptor-based virtual screening (VS) respectively have been discussed. Expert opinion: Along with conventional techniques, computer-aided VS, molecular modeling and docking studies have been applied for drug design, discovery and development. Computer-aided tools provide a rational way to explain pharmacological activities of topos inhibitors under study. Comparative study of crystal structures of topo I/II-DNA-drug ternary complex and use of appropriate pharmacological screening methods will lead to potential anticancer drugs in the coming days.