Discovery of a Novel Triazolopyridine Derivative as a Tankyrase Inhibitor.

More than 80% of colorectal cancer patients have adenomatous polyposis coli (APC) mutations, which induce abnormal WNT/ß-catenin activation. Tankyrase (TNKS) mediates the release of active ß-catenin, which occurs regardless of the ligand that translocates into the nucleus by AXIN degradation via the ubiquitin-proteasome pathway. Therefore, TNKS inhibition has emerged as an attractive strategy for cancer therapy. In this study, we identified pyridine derivatives by evaluating in vitro TNKS enzyme activity and investigated N-([1,2,4]triazolo[4,3-a]pyridin-3-yl)-1-(2-cyanophenyl)piperidine-4-carboxamide (TI-12403) as a novel TNKS inhibitor. TI-12403 stabilized AXIN2, reduced active ß-catenin, and downregulated ß-catenin target genes in COLO320DM and DLD-1 cells. The antitumor activities of TI-12403 were confirmed by the viability of the colorectal cancer cells and its lack of visible toxicity in DLD-1 xenograft mouse model. In addition, combined 5-FU and TI-12403 treatment synergistically inhibited proliferation to a greater extent than that in a single drug treatment. Our observations suggest that TI-12403, a novel selective TNKS1 inhibitor, may be a suitable compound for anticancer drug development.

Molecular mechanisms underlying the effects of the small molecule AMC-04 on apoptosis: Roles of the activating transcription factor 4-C/EBP homologous protein-death receptor 5 pathway.

The unfolded protein response (UPR) is an emerging target pathway for cancer treatment owing to its ability to induce cell death. In our previous analysis of UPR-modulating small molecules, we had reported that piperazine oxalate derivative compounds (AMC-01-04) are able to promote increased phosphorylation of eukaryotic translation initiation factor-2 alpha (eIF2α). In this study, we found that AMC-04 induces apoptotic cell death via the activation of UPR in human breast and liver cancer cells. AMC-04 upregulated the expression of activating transcription factor-4 (ATF4)-C/EBP homologous protein (CHOP) and death receptor 5 (DR5) in cancer cells, as revealed by microarray analysis, small-interference RNA assay, and western blotting. From a mechanistic perspective, cytotoxic UPR pathway activation by AMC-04 is mediated by reactive oxygen species (ROS) and p38 mitogen-activated protein kinase (p38 MAPK) signaling. A chemical informatics approach predicted that AMC-04 modulates histone methyltransferase activity. Based on biochemical analysis, the activity of histone methyltransferases, including SUV39H1, SUV39H2, SETDB1, and EHMT1, was inhibited by AMC-04. Furthermore, chemical inhibition of the identified target proteins induced UPR activation and apoptotic cell death, suggesting that inhibition of histone methyltransferases is a promising strategy for cancer therapy. Taken together, we showed that the small molecule AMC-04 modulates epigenetic enzyme activity and mediates the link between cytotoxic UPR and histone modifications.

Hot spot profiles of SARS-CoV-2 and human ACE2 receptor protein protein interaction obtained by density functional tight binding fragment molecular orbital method.

The prevalence of a novel ß-coronavirus (SARS-CoV-2) was declared as a public health emergency of international concern on 30 January 2020 and a global pandemic on 11 March 2020 by WHO. The spike glycoprotein of SARS-CoV-2 is regarded as a key target for the development of vaccines and therapeutic antibodies. In order to develop anti-viral therapeutics for SARS-CoV-2, it is crucial to find amino acid pairs that strongly attract each other at the interface of the spike glycoprotein and the human angiotensin-converting enzyme 2 (hACE2) complex. In order to find hot spot residues, the strongly attracting amino acid pairs at the protein-protein interaction (PPI) interface, we introduce a reliable inter-residue interaction energy calculation method, FMO-DFTB3/D/PCM/3D-SPIEs. In addition to the SARS-CoV-2 spike glycoprotein/hACE2 complex, the hot spot residues of SARS-CoV-1 spike glycoprotein/hACE2 complex, SARS-CoV-1 spike glycoprotein/antibody complex, and HCoV-NL63 spike glycoprotein/hACE2 complex were obtained using the same FMO method. Following this, a 3D-SPIEs-based interaction map was constructed with hot spot residues for the hACE2/SARS-CoV-1 spike glycoprotein, hACE2/HCoV-NL63 spike glycoprotein, and hACE2/SARS-CoV-2 spike glycoprotein complexes. Finally, the three 3D-SPIEs-based interaction maps were combined and analyzed to find the consensus hot spots among the three complexes. As a result of the analysis, two hot spots were identified between hACE2 and the three spike proteins. In particular, E37, K353, G354, and D355 of the hACE2 receptor strongly interact with the spike proteins of coronaviruses. The 3D-SPIEs-based map would provide valuable information to develop anti-viral therapeutics that inhibit PPIs between the spike protein of SARS-CoV-2 and hACE2.

PMFF: Development of a Physics-Based Molecular Force Field for Protein Simulation and Ligand Docking.

The physics-based molecular force field (PMFF) was developed by integrating a set of potential energy functions in which each term in an intermolecular potential energy function is derived based on experimental values, such as the dipole moments, lattice energy, proton transfer energy, and X-ray crystal structures. The term "physics-based" is used to emphasize the idea that the experimental observables that are considered to be the most relevant to each term are used for the parameterization rather than parameterizing all observables together against the target value. PMFF uses MM3 intramolecular potential energy terms to describe intramolecular interactions and includes an implicit solvation model specifically developed for the PMFF. We evaluated the PMFF in three ways. We concluded that the PMFF provides reliable information based on the structure in a biological system and interprets the biological phenomena accurately by providing more accurate evidence of the biological phenomena.

Cyclase-associated protein 1 is a binding partner of proprotein convertase subtilisin/kexin type-9 and is required for the degradation of low-density lipoprotein receptors by proprotein convertase subtilisin/kexin type-9.

AIMS: Proprotein convertase subtilisin/kexin type-9 (PCSK9), a molecular determinant of low-density lipoprotein (LDL) receptor (LDLR) fate, has emerged as a promising therapeutic target for atherosclerotic cardiovascular diseases. However, the precise mechanism by which PCSK9 regulates the internalization and lysosomal degradation of LDLR is unknown. Recently, we identified adenylyl cyclase-associated protein 1 (CAP1) as a receptor for human resistin whose globular C-terminus is structurally similar to the C-terminal cysteine-rich domain (CRD) of PCSK9. Herein, we investigated the role of CAP1 in PCSK9-mediated lysosomal degradation of LDLR and plasma LDL cholesterol (LDL-C) levels. METHODS AND RESULTS: The direct binding between PCSK9 and CAP1 was confirmed by immunoprecipitation assay, far-western blot, biomolecular fluorescence complementation, and surface plasmon resonance assay. Fine mapping revealed that the CRD of PCSK9 binds with the Src homology 3 binding domain (SH3BD) of CAP1. Two loss-of-function polymorphisms found in human PCSK9 (S668R and G670E in CRD) were attributed to a defective interaction with CAP1. siRNA against CAP1 reduced the PCSK9-mediated degradation of LDLR in vitro. We generated CAP1 knock-out mice and found that the viable heterozygous CAP1 knock-out mice had higher protein levels of LDLR and lower LDL-C levels in the liver and plasma, respectively, than the control mice. Mechanistic analysis revealed that PCSK9-induced endocytosis and lysosomal degradation of LDLR were mediated by caveolin but not by clathrin, and they were dependent on binding between CAP1 and caveolin-1. CONCLUSION: We identified CAP1 as a new binding partner of PCSK9 and a key mediator of caveolae-dependent endocytosis and lysosomal degradation of LDLR.

Investigation of Hot Spot Region in XIAP Inhibitor Binding Site by Fragment Molecular Orbital Method.

X-linked inhibitor of apoptosis protein (XIAP) is an important regulator of cancer cell survival whose BIR3 domain (XIAP-BIR3) recognizes the Smac N-terminal tetrapeptide sequence (AVPI), making it an attractive protein-protein interaction (PPI) target for cancer therapies. We used the fragment molecular orbital (FMO) method to study the binding modes and affinities between XIAP-BIR3 and a series of its inhibitors (1-8) that mimic the AVPI binding motif; the inhibitors had common interactions with key residues in a hot spot region of XIAP-BIR3 (P1-P4 subpockets) with increased binding affinity mainly attributed to specific interactions with the P1 and P4 subpockets. Based on the structural information from FMO results, we proposed a novel XIAP natural product inhibitor, neoeriocitrin 10, which was derived from our preciously reported XIAP-BIR3 inhibitor 9, can be used as a highly potent candidate for XIAP-BIR3 inhibition. We also performed pair interaction energy decomposition analysis to investigate the binding energies between specific binding residues and individual ligands, showing that the novel natural product neoeriocitrin 10 had a higher binding affinity than epicatechin gallate 9. Molecular docking and dynamics simulations were performed to explore the mode of binding between 10 and XIAP-BIR3, demonstrating that 10 binds more strongly to the P1 and P4 pockets than 9. Overall, we present a novel natural product, neoeriocitrin 10, and demonstrate that the FMO method can be used to identify hot spots in PPIs and design new compounds for XIAP inhibition.

Radiosensitizing Effect of Novel Phenylpyrimidine Derivatives on Human Lung Cancer Cells via Cell Cycle Perturbation.

Radiotherapy is one of the most common treatments for cancer, but radioresistance and injury to normal tissue are considered major obstacles to successful radiotherapy. Thus, there is an urgent need to develop radiosensitizers to improve the therapeutic outcomes of radiotherapy in cancer patients. Our previous efforts to identify novel radiosensitizers, using high-throughput screening targeting p53 and Nrf2 revealed a promising N-phenylpyrimidin-2-amine (PPA) lead compound. In the present study, 17 derivatives of this lead compound were examined, and it was found that 4-(4-fluorophenyl)-N-(4-nitrophenyl)-6-phenylpyrimidin-2-amine (PPA5), 4-((4-(4-fluorophenyl)pyrimidin-2-yl)amino)-3-methoxy-N-methyl -benzamide (PPA13), 4-((4-(4-fluorophenyl)pyrimidin-2-yl)amino)benzenesulfonamide (PPA14), 4-((4-(2-chlorophenyl)pyrimidin-2-yl)amino)benzenesulfonamide (PPA15), and 4-((4-(2-chlorophenyl)pyrimidin-2-yl)amino)-N-methylbenzamide (PPA17) inhibited cell viability by more than 50%, with a marked increase in the proportion of cells arrested at the G2/M phase of cell cycle. Among these compounds, PPA15 markedly increased the sub-G1 cell population and increased the levels of cyclin B1 and the phosphorylation levels of cyclin-dependent kinase (CDK) 1. Combined treatment with radiation and PPA14 or PPA15 significantly decreased clonogenic survival. An in vitro kinase assay revealed that PPA15 inhibited multiple CDKs involved in cell cycle regulation. Compared with drug or radiation treatment alone, combined treatment with PPA15 and radiation resulted in the suppression of A549 tumor growth in mice by 59.5% and 52.7%, respectively. Treatment with PPA15 alone directly inhibited tumor growth by 25.7%. These findings suggest that the novel pan CDK inhibitor, PPA15, may be a promising treatment to improve the effectiveness of radiotherapy for the treatment of cancer. SIGNIFICANCE STATEMENT: Several inhibitors of CDK have been successfully evaluated in combination with other chemotherapeutics in clinical trials, but negative side effects have partially restricted their clinical use. In this study, we identified a novel pan-CDK inhibitor to increase radiosensitivity, and we hope this work will encourage the development of promising small-molecule radiosensitizers.

The small molecule AU14022 promotes colorectal cancer cell death via p53-mediated G2/M-phase arrest and mitochondria-mediated apoptosis.

The p53 tumor suppressor plays critical roles in cell cycle regulation and apoptotic cell death, with its activation capable of sensitizing cancer cells to radiotherapy or chemotherapy. To identify small molecules that induce apoptosis via increased p53 transcriptional activity, we used a novel in-house library containing 96 small-molecule compounds. Using a cell-based screening method with a p53-responsive luciferase-reporter assay system involving benzoxazole derivatives, we found that AU14022 administration significantly increased p53 transcriptional activity in a concentration-dependent manner. Treatment with AU14022 increased p53 protein expression, p53 Ser15 phosphorylation, p53-mediated expression of downstream target genes, and apoptosis in p53-wild-type HCT116 human colon cancer cells, but not in p53-knockout HCT116 cells. Additionally, p53-wild-type HCT116 cells treated with AU14022 exhibited mitochondrial dysfunction, including modulated expression of B-cell lymphoma-2 family proteins and cytochrome c release. Combination treatment with AU14022 and ionizing radiation (IR) synergistically induced apoptosis as compared with IR or AU14022 treatment alone, with further investigation demonstrating that cell cycle progression was significantly arrested at the G2/M phase following AU14022 treatment. Furthermore, in a mouse p53-wild-type HCT116 colon cancer xenograft model, combined treatment with AU14022 and IR inhibited tumor growth more effectively than radiation alone. Therefore, AU14022 treatment induced apoptosis through p53-mediated cell cycle arrest involving mitochondrial dysfunction, leading to enhanced radiosensitivity in colon cancer cells. These results provide a basis for further assessments of AU14022 as a promising anticancer agent.

Novel focal adhesion kinase 1 inhibitor sensitizes lung cancer cells to radiation in a p53-independent manner.

Focal adhesion kinase 1 (FAK1) is known to promote tumor progression and metastasis by controlling cell movement, invasion, survival and the epithelial-to-mesenchymal transition in the tumor microenvironment. As recent reports imply that FAK1 is highly associated with tumor cell development and malignancy, the inhibition of FAK1 activity could be an effective therapeutic approach for inhibiting the growth and metastasis of tumor cells. In this study, we aimed to determine the effect of a novel synthetic FAK1 inhibitor 2-[2-(2-methoxy-4-morpholin-4-yl-phenylamino)-5-trifluoromethyl-pyrimidin-4-ylamino]-N-methyl-benzamide, (MPAP) on lung cancer cells. MPAP suppressed cancer cell proliferation and the phosphorylation of FAK1. Combined treatment with MPAP and irradiation (IR) showed enhanced suppression of cancer cell proliferation in wild-type p53 cells and more intense suppression in p53-null cells. In addition, the combination treatment effectively induced G1 cell cycle arrest in a p53-independent manner. In an in vivo tumor xenograft mouse model, treatment with both MPAP and IR reduced tumor growth more than the treatment with IR or MPAP alone. Overall, these data demonstrate that the radiosensitizing effect of MPAP is mediated by the regulation of retinoblastoma protein (RB) phosphorylation in a p53-independent manner.

The small molecule '1-(4-biphenylylcarbonyl)-4-(5-bromo-2-methoxybenzyl) piperazine oxalate' and its derivatives regulate global protein synthesis by inactivating eukaryotic translation initiation factor 2-alpha.

By environmental stresses, cells can initiate a signaling pathway in which eukaryotic translation initiation factor 2-alpha (eIF2-α) is involved to regulate the response. Phosphorylation of eIF2-α results in the reduction of overall protein neogenesis, which allows cells to conserve resources and to reprogram energy usage for effective stress control. To investigate the role of eIF2-α in cell stress responses, we conducted a viability-based compound screen under endoplasmic reticulum (ER) stress condition, and identified 1-(4-biphenylylcarbonyl)-4-(5-bromo-2-methoxybenzyl) piperazine oxalate (AMC-01) and its derivatives as eIF2-α-inactivating chemical. Molecular characterization of this signaling pathway revealed that AMC-01 induced inactivation of eIF2-α by phosphorylating serine residue 51 in a dose- and time-dependent manner, while the negative control compounds did not affect eIF2-α phosphorylation. In contrast with ER stress induction by thapsigargin, phosphorylation of eIF2-α persisted for the duration of incubation with AMC-01. By pathway analysis, AMC-01 clearly induced the activation of protein kinase RNA-activated (PKR) kinase and nuclear factor-κB (NF-κB), whereas it did not modulate the activity of PERK or heme-regulated inhibitor (HRI). Finally, we could detect a lower protein translation rate in cells incubated with AMC-01, establishing AMC-01 as a potent chemical probe that can regulate eIF2-α activity. We suggest from these data that AMC-01 and its derivative compounds can be used as chemical probes in future studies of the role of eIF2-α in protein synthesis-related cell physiology.

Inhibition of cancer cell invasion by new ((3,4-dihydroxy benzylidene)hydrazinyl)pyridine-3-sulfonamide analogs.

Rab GTPases regulate various types of intracellular membrane trafficking in all eukaryotes. Since Rab27a and its multiple effectors are involved in exocytosis of lysosome-related organelles and play a major role in malignancy, compounds targeting Rab27a could be likely used to inhibit invasive growth and tumor metastasis. Thus, we designed and synthesized several compounds based on the previously reported Rab27a-targeting synthetic compounds identified by virtual screening, and investigated their anti-metastatic effects in MDA-MB231 and A375 cells. Among the synthesized compounds, (E)-N-(3-chlorophenyl)-6-(2-(3,4-dihydroxy benzylidene)hydrazinyl)pyridine-3-sulfonamide (3d) and (E)-N-benzyl-6-(2-(3,4-dihydroxy benzylidene)hydrazinyl)-N-methylpyridine-3-sulfonamide (3f) significantly inhibited the invasiveness of both tumor cell lines. Compounds 3d and 3f also decreased the levels of signature extracellular matrix marker proteins (fibronectin, collagen, and α-smooth muscle actin) and representative mesenchymal cell markers (N-cadherin and vimentin). Taken together, our results suggest that novel sulfonamide analogs have anti-metastatic activity in breast and melanoma cancer cell lines and may be used as therapeutic agents to treat malignant cancer.

Identification of a Small Benzamide Inhibitor of Influenza Virus Using a Cell-Based Screening.

BACKGROUND: The zoonotic transmission of highly pathogenic avian influenza viruses and the global pandemic of H1N1 influenza in 2009 signified the need for a wider coverage of therapeutic options for the control of influenza. METHODS: An in-house compound library was screened using a cytopathic effect inhibition assay. Selected hits were then tested in vivo and used as a core skeleton for derivative synthesis. RESULTS: The hit compound (BMD-2601505) was effective [50% effective concentration (EC50) of 60-70 µM] in reducing the death rate of cells infected with human influenza A and B viruses as well as avian influenza A virus. Furthermore, BMD-2601505 reduced the weight loss and increased the survival after lethal infection. The compound was further modified to enhance its antiviral potency. Results show that one derivative with bromobenzene moiety was most effective (EC50 of 22-37 µM) against the influenza viruses tested. CONCLUSION: We identified a small benzamide compound exhibiting antiviral activity against influenza viruses. The results warrant further evaluation of antiviral activities against drug-resistant influenza isolates.

The HSP90 inhibitor, NVP-AUY922, sensitizes KRAS-mutant non-small cell lung cancer with intrinsic resistance to MEK inhibitor, trametinib.

RAS-driven tumors are often difficult to treat with conventional therapies and therefore, novel treatment strategies are necessary. The present study describes a promising targeted therapeutic strategy against non-small cell lung cancer (NSCLC) harboring KRAS mutations, which has intrinsic resistance to MEK inhibition. Results showed that intrinsic resistance to MEK inhibition occurred via high AKT expression by PI3K activation as a bypass pathway. The HSP90 inhibitor AUY922 suppressed PI3K-AKT-mTOR and RAF-MEK-ERK, and rendered cells sensitive to trametinib (GSK1120212). Synergy from the combination of the two drugs was observed in only sub-therapeutic concentrations of either drug. Dual inhibition of the HSP90 and MEK signaling pathways with sub-therapeutic doses may represent a potent therapeutic strategy to treat KRAS-mutant NSCLC with intrinsic resistance to MEK inhibition and to resolve the toxicity observed upon dual inhibition of AKT and MEK at therapeutic doses in clinical trials.

IM-412 inhibits the invasion of human breast carcinoma cells by blocking FGFR-mediated signaling.

Triple-negative breast cancer (TNBC) is an aggressive cancer with a poor prognosis due to its epithelial­to-mesenchymal transition (EMT) phenotype. Cancer patients often experience several detrimental effects of cancer treatment, such as chemoresistance, radioresistance and the maintenance of cancer stem cells due to EMT. Thus, EMT signaling is considered to be a valuable therapeutic target for cancer treatment, and its inhibition is being attempted as a new treatment option for TNBC patients. Previously, we showed that 3-(2-chlorobenzyl)-1,7-dimethyl-1H-imidazo[2,1-f]purine­2,4(3H,8H)-dione (IM-412) inhibits transforming growth factor-ß (TGF-ß)-induced differentiation of human lung fibroblasts through both Smad-dependent and -independent pathways. In the present study, we examined the inhibitory effect of IM-412 on EMT pathways and invasiveness in TNBC cells since the TGF-ß signaling pathway is a typical signaling pathway that functions in EMT. IM-412 not only potently suppressed the migration and invasion of MDA-MB-231 cells, but also lowered the expression of mesenchymal markers and EMT-activating transcription factors in these cells. IM-412 inhibited the activation of several signaling proteins, including Smad2/Smad3, p38MAPK, Akt and JNK, and it also attenuated the phosphorylation of FGFR1 and FGFR3. Collectively, our findings suggest that the synthetic compound IM-412 suppressed the EMT process in MDA-MB-231 cells and thereby effectively inhibited the migration and invasion of these cancer cells. Thus, IM-412 could serve as a novel therapeutic agent for malignant cancers.

Discovery of 11ß-hydroxysteroid dehydrogenase type 1 inhibitor.

Various adamantane sulfonamides showed potent inhibitory activity against 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1). In continuation of our efforts to discover a more potent, selective and metabolically stable 11ß-HSD1 inhibitor in mice as well as in humans, we optimized the adamantane sulfonamide using structure-based molecular modeling. Compound 3, which has alkyl side chains on the linker, demonstrated a potent inhibitory activity against human and mouse 11ß-HSD1 (IC50 of 0.6 nM and 26 nM, respectively) and good physicochemical properties as a new anti-diabetes drug candidate.

Modulation of intracellular calcium levels by calcium lactate affects colon cancer cell motility through calcium-dependent calpain.

Cancer cell motility is a key phenomenon regulating invasion and metastasis. Focal adhesion kinase (FAK) plays a major role in cellular adhesion and metastasis of various cancers. The relationship between dietary supplementation of calcium and colon cancer has been extensively investigated. However, the effect of calcium (Ca2+) supplementation on calpain-FAK-motility is not clearly understood. We sought to identify the mechanism of FAK cleavage through Ca2+ bound lactate (CaLa), its downstream signaling and role in the motility of human colon cancer cells. We found that treating HCT116 and HT-29 cells with CaLa immediately increased the intracellular Ca2+ (iCa2+) levels for a prolonged period of time. Ca2+ influx induced cleavage of FAK into an N-terminal FAK (FERM domain) in a dose-dependent manner. Phosphorylated FAK (p-FAK) was also cleaved in to its p-N-terminal FAK. CaLa increased colon cancer cells motility. Calpeptin, a calpain inhibitor, reversed the effects of CaLa on FAK and pFAK cleavage in both cancer cell lines. The cleaved FAK translocates into the nucleus and modulates p53 stability through MDM2-associated ubiquitination. CaLa-induced Ca2+ influx increased the motility of colon cancer cells was mediated by calpain activity through FAK and pFAK protein destabilization. In conclusion, these results suggest that careful consideration may be given in deciding dietary Ca2+ supplementation to patient undergoing treatment for metastatic cancer.

A novel highly potent and selective 11ß-hydroxysteroid dehydrogenase type 1 inhibitor, UI-1499.

AIMS: Elevated levels of glucocorticoid hormones cause glucose intolerance, visceral obesity, insulin resistance, hypertension, and dyslipidemia. 11ß-Hydroxysteroid dehydrogenase type 1 (11ß-HSD1) represents as an attractive therapeutic target for treatment of metabolic syndrome and type 2 diabetes. This study investigated whether 11ß-HSD1 inhibition by a novel selective inhibitor, (1S,3R,4S,5S,7S)-4-(1-((2-fluoro-N-methylphenylsulfonamido)-methyl) cyclopropanecarboxamido) adamantane-1-carboxamide (UI-1499) ameliorated metabolic abnormalities in diabetic mice. MAIN METHODS: The in vitro activity of 11ß-HSD1 was measured using the homogeneous time resolved fluorescence (HTRF) assay. Differentiated adipocytes were used to evaluate cellular 11ß-HSD1 activity. To determine the inhibitory effects on 11ß-HSD1 in tissues, we performed ex vivo studies using liver and epididymal fat isolated from C57BL/6J mice. KKAy mice were administered with UI-1499 to evaluate whether this compound ameliorated metabolic abnormalities in vivo in diabetic animals. KEY FINDINGS: UI-1499 had highly potent inhibitory activity in mouse, monkey and human 11ß-HSD1, derived from liver microsomes. Oral administration of 45 mg/kg UI-1499 significantly inhibited 11ß-HSD1 activity in C57BL/6J mouse liver and epididymal fat tissues. In KKAy mice, oral administration of UI-1499 (10 and 30 mg/kg for 3 weeks) lowered fasting blood glucose and HbA1c levels; these effects were comparable to those of pioglitazone. Further, UI-1499 treatment lowered plasma low-density lipoprotein (LDL) level in KKAy mice. SIGNIFICANCE: These results suggest that the 11ß-HSD1 inhibitor, UI-1499, may serve as a novel drug candidate for the treatment of type 2 diabetes and metabolic syndrome.

Design and synthesis of a cell-permeable, drug-like small molecule inhibitor targeting the polo-box domain of polo-like kinase 1.

BACKGROUND: Polo-like kinase-1 (Plk1) plays a crucial role in cell proliferation and the inhibition of Plk1 has been considered as a potential target for specific inhibitory drugs in anti-cancer therapy. Several research groups have identified peptide-based inhibitors that target the polo-box domain (PBD) of Plk1 and bind to the protein with high affinity in in vitro assays. However, inadequate proteolytic resistance and cell permeability of the peptides hinder the development of these peptide-based inhibitors into novel therapeutic compounds. METHODOLOGY/PRINCIPAL FINDINGS: In order to overcome the shortcomings of peptide-based inhibitors, we designed and synthesized small molecule inhibitors. Among these molecules, bg-34 exhibited a high binding affinity for Plk1-PBD and it could cross the cell membrane in its unmodified form. Furthermore, bg-34-dependent inhibition of Plk1-PBD was sufficient for inducing apoptosis in HeLa cells. Moreover, modeling studies performed on Plk1-PBD in complex with bg-34 revealed that bg-34 can interact effectively with Plk1-PBD. CONCLUSION/SIGNIFICANCE: We demonstrated that the molecule bg-34 is a potential drug candidate that exhibits anti-Plk1-PBD activity and possesses the favorable characteristics of high cell permeability and stability. We also determined that bg-34 induced apoptotic cell death by inhibiting Plk1-PBD in HeLa cells at the same concentration as PEGylated 4j peptide, which can inhibit Plk1-PBD activity 1000 times more effectively than bg-34 can in in vitro assays. This study may help to design and develop drug-like small molecule as Plk1-PBD inhibitor for better therapeutic activity.

Adenylyl cyclase-associated protein 1 is a receptor for human resistin and mediates inflammatory actions of human monocytes.

Human resistin is a cytokine that induces low-grade inflammation by stimulating monocytes. Resistin-mediated chronic inflammation can lead to obesity, atherosclerosis, and other cardiometabolic diseases. Nevertheless, the receptor for human resistin has not been clarified. Here, we identified adenylyl cyclase-associated protein 1 (CAP1) as a functional receptor for human resistin and clarified its intracellular signaling pathway to modulate inflammatory action of monocytes. We found that human resistin directly binds to CAP1 in monocytes and upregulates cyclic AMP (cAMP) concentration, protein kinase A (PKA) activity, and NF-κB-related transcription of inflammatory cytokines. Overexpression of CAP1 in monocytes enhanced the resistin-induced increased activity of the cAMP-dependent signaling. Moreover, CAP1-overexpressed monocytes aggravated adipose tissue inflammation in transgenic mice that express human resistin from their monocytes. In contrast, suppression of CAP1 expression abrogated the resistin-mediated inflammatory activity both in vitro and in vivo. Therefore, CAP1 is the bona fide receptor for resistin leading to inflammation in humans.

Identification of novel rab27a/melanophilin blockers by pharmacophore-based virtual screening.

Melanocytes are unique cells that produce specific melanin-containing intracellular organelles called melanosomes. Melanosomes are transported from the perinuclear area of melanocytes toward the plasma membrane as they become more melanized in order to increase skin pigmentation. In this vesicular trafficking of melanosomes, Rab27a, melanophilin, and myosin Va play crucial roles in linking melanosomes to actin-based motors. To identify novel compounds to inhibit binding interface between Rab27a and melanophilin, a pharmacophore model was built based on a modeled 3D structure of the protein complex that describes the essential binding residues in the intermolecular interaction. A pharmacophore model was employed to screen a chemical library database. Finally, 25 virtual hits were selected for biological evaluations. The biological activities of 11 analogues were evaluated in a second assay. Two compounds were identified as having concentration-dependent inhibitory activity. By analyzing structure-activity relationships of derivatives of BMD-20, two hydroxyl functional groups were found to be critical for blocking the intermolecular binding between Rab27a and melanophilin.