The antitumor activity of a novel GCN2 inhibitor in head and neck squamous cell carcinoma cell lines.

BACKGROUND: General control nonderepressible 2 (GCN2) senses amino acid deprivation and activates activating transcription factor 4 (ATF4), which regulates many adaptive genes. We evaluated the impact of AST-0513, a novel GCN2 inhibitor, on the GCN2-ATF4 pathway. Additionally, we evaluated the antitumor effects of AST-0513 in amino acid deprivation in head and neck squamous cell carcinoma (HNSCC) cell lines. METHODS: GCN2 expression in HNSCC patient tissues was measured by immunohistochemistry. Five HNSCC cell lines (SNU-1041, SNU-1066, SNU-1076, Detroit-562, FaDu) grown under amino acid deprivation conditions, were treated with AST-0513. After AST-0513 treatment, cell proliferation was measured by CCK-8 assay. Flow cytometry was used to evaluate apoptosis and cell cycle phase. In addition, immunoblotting was performed to evaluate the effect of AST-0513 on the GCN2-ATF4 pathway, cell cycle arrest, and apoptosis. RESULTS: We demonstrated that GCN2 was highly expressed in HNSCC patient tissues. AST-0513 inhibited the GCN2-ATF4 pathway in all five HNSCC cell lines. Inhibiting the GCN2-ATF4 pathway during amino acid deprivation reduced HNSCC cell proliferation and prevented adaptation to nutrient stress. Moreover, AST-0513 treatment led to p21 and Cyclin B1 accumulation and G2/M phase cycle arrest. Also, apoptosis was increased, consistent with increased bax expression, increased bcl-xL phosphorylation, and decreased bcl-2 expression. CONCLUSION: A novel GCN2 inhibitor, AST-0513, inhibited the GCN2-ATF4 pathway and has antitumor activity that inhibits proliferation and promotes cell cycle arrest and apoptosis. Considering the high expression of GCN2 in HNSCC patients, these results suggest the potential role of GCN2 inhibitor for the treatment of HNSCC.

Aristolactam BIII, a naturally derived DYRK1A inhibitor, rescues Down syndrome-related phenotypes.

BACKGROUND: Dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) is a significant pathogenic factor in Down syndrome (DS), wherein DYRK1A is overexpressed by 1.5-fold because of trisomy of human chromosome 21. Thus, DYRK1A inhibition is considered a therapeutic strategy to modify the disease. PURPOSE: This study aims to identify a novel DYRK1A inhibitor and validate its therapeutic potential in DS-related pathological conditions. STUDY DESIGN: In order to identify a novel DYRK1A inhibitor, we carried out two-step screening: a structure-based virtual screening of > 300,000 chemical library (first step) and cell-based nuclear factor of activated T-cells (NFAT)-response element (RE) promoter assay (second step). Primary hits were evaluated for their DYRK1A inhibitory activity using in vitro kinase assay and Tau phosphorylation in mammalian cells. Confirmed hit was further evaluated in pathological conditions including DYRK1A-overexpressing fibroblasts, flies, and mice. RESULTS: We identified aristolactam BIII, a natural product derived from herbal plants, as a novel DYRK1A inhibitor. It potently inhibited the kinase activity of DYRK1A in vitro (IC50 = 9.67 nM) and effectively suppressed DYRK1A-mediated hyperphosphorylation of Tau in mammalian cells. Aristolactam BIII rescued the proliferative defects of DYRK1A transgenic (TG) mouse-derived fibroblasts and neurological and phenotypic defects of DS-like Drosophila models. Oral administration of aristolactam BIII acutely suppressed Tau hyperphosphorylation in the brain of DYRK1A TG mice. In the open field test, aristolactam BIII significantly ameliorated the exploratory behavioral deficit of DYRK1A TG mice. CONCLUSION: Our work revealed that aristolactam BIII as a novel DYRK1A inhibitor rescues DS phenotypes in cells and in vivo and suggested its therapeutic potential for the treatment of DYRK1A-related diseases.

Two-Photon Probe for TNF-α. Assessment of the Transmembrane TNF-α Level in Human Colon Tissue by Two-Photon Microscopy.

We developed Pyr1-infliximab: a two-photon probe for TNF-α. Pyr1-infliximab showed absorption maxima at 280 and 438 nm and an emission maximum at 610 nm in an aqueous buffer and effective two-photon action cross-section values of (520-2830) × 10-50 cm4s/photon in RAW 264.7 cells. After this probe was labeled, it was possible to detect Pyr1-infliximab-transmembrane TNF-α complexes in a live cell and to determine the relative proportion of these complexes in human colon tissues. This proportion among healthy, possibly inflamed, and inflamed tissues of patients with ulcerative colitis was found to be 1.0/4.5/10. This probe may find useful applications for selective detection of transmembrane TNF-α in a live cell or tissue, for quantification of inflammation in human colon tissue or of antidrug antibodies in patients who stop responding to anti-TNF therapy, and for monitoring of the response to this therapy.

αVß3-Targeted Delivery of Camptothecin-Encapsulated Carbon Nanotube-Cyclic RGD in 2D and 3D Cancer Cell Culture.

Integrin αvß3 is widely expressed in various types of human cancer lines and plays a key role in angiogenesis for tumor growth and metastasis. Delivery of therapeutics to αvß3-expressing tumors can thus be a promising approach for treating cancer. For targeted delivery of anticancer therapeutics to αvß3-expressing tumor cells, cyclic arginylglycylaspartic acid (RGD) peptide was covalently conjugated to the surface of carboxylic acid-functionalized carbon nanotubes (fCNTs), and the topoisomerase I inhibitor camptothecin (CPT) was encapsulated in the fCNTs (CPT@fCNT-RGD). CPT@fCNT-RGD was successfully delivered to αvß3-expressing A375 cells, and compared with nontargeted CPT@fCNT, it provided 3.78- and 3.02-fold increases in the anticancer effect in 2D and 3D culture. Analysis of apoptosis-related gene expression shows that the expression levels of Bax, cleaved caspase-3, and nuclear factor kappa-light-chain-enhancer of activated B cells were significantly increased in A375 cells incubated with CPT@fCNT-RGD compared with those incubated with CPT@fCNT. These results suggest that cyclic RGD-conjugated CNTs encapsulating an anticancer therapeutic can be a promising platform for treating cancer.

A natural compound, aristoyagonine, is identified as a potent bromodomain inhibitor by mid-throughput screening.

Bromodomain-containing protein 4 (Brd4) is known to play a key role in tumorigenesis. It binds acetylated histones to regulate the expression of numerous genes. Because of the importance of brd4 in tumorigenesis, much research has been undertaken to develop brd4 inhibitors with therapeutic potential. As a result, various scaffolds for bromodomain inhibitors have been identified. To discover new scaffolds, we performed mid-throughput screening using two different enzyme assays, alpha-screen and ELISA. We found a novel bromodomain inhibitor with a unique scaffold, aristoyagonine. This natural compound showed inhibitory activity in vitro and tumor growth inhibition in a Ty82-xenograft mouse model. In addition, we tested Brd4 inhibitors in gastric cancer cell lines, and found that aristoyagonine exerted cytotoxicity not only in I-BET-762-sensitive cancer cells, but also in I-BET-762-resistant cancer cells. This is the first paper to describe a natural compound as a Brd4 bromodomain inhibitor.

Two-Photon Probes for pH: Detection of Human Colon Cancer using Two-Photon Microscopy.

We have developed two-photon (TP) pH-sensitive probes (BH-2 and BHEt-1) that exhibit absorption and emission maxima at 370 and 466 nm, and TP absorption cross-section values of 51 and 61 GM (1 GM = 10-50cm4s/photon), respectively, at 750 nm and pH 3.0 in a universal buffer (0.1 M citric acid, 0.1 M KH2PO4, 0.1 M Na2B4O7, 0.1 M Tris, 0.1 M KCl)/1,4-dioxane (7/3) solution. The TPM images of CCD-18co (a normal colon cell line) and HCT116 cells (a colon cancer cell line) labeled with BH-2 were too dim to be distinguished. When the same cells were labeled with BHEt-1, however, the TPM image of the HCT116 cells was much brighter than that of CCD-18co cells, and the relative proportion of the acidic vesicles (Pacid) of the former was 5-fold larger than that of latter. BHEt-1 could also differentiate HepG2 cells (a human liver cancer cell line) from LX-2 cells (a human hepatic stellate cell line) with a 6-fold larger Pacid value. Human colon cancer tissues labeled with BHEt-1 showed similar results, demonstrating much brighter TPM images and 6-fold larger Pacid values compared to normal tissue. These results suggest the potential utility of BHEt-1 for detecting colon cancer in human tissues using TPM.

Identification of small-molecule compounds targeting the dishevelled PDZ domain by virtual screening and binding studies.

The Dishevelled (Dvl) protein, which conveys signals from receptors to the downstream effectors, is a critical constituent of the Wnt/ß-catenin signaling pathway. Because the PDZ domain of Dvl protein functions through associations with a wide range of protein partners, Dvl protein involved in the Wnt signaling pathway has been considered to be therapeutic targets in cancers. In this study, we performed structure-based pharmacophore model of the Dvl PDZ domain to discover novel small-molecule binders and identified eight compounds with micromolar affinity. The most potent compound identified, BMD4702, efficiently bound to the Dvl PDZ domain with 11.2µM affinity and had a 0.186µM KD value according to surface plasmon resonance and fluorescence spectroscopy, respectively. Combining both structural-kinetic relationship analyses and docking studies, we fourmulated that the ligand-binding site is composed of three H-bonds and three hydrophobic features. Thus, our approach led to the identification of potent binders of the Dvl PDZ domain and the findings provide novel insights into structure-based approaches to design high-affinity binders for the Dvl PDZ domain.

Small molecule inhibitors of the Dishevelled-CXXC5 interaction are new drug candidates for bone anabolic osteoporosis therapy.

Bone anabolic agents promoting bone formation and rebuilding damaged bones would ideally overcome the limitations of anti-resorptive therapy, the current standard prescription for osteoporosis. However, the currently prescribed parathyroid hormone (PTH)-based anabolic drugs present limitations and adverse effects including osteosarcoma during long-term use. Also, the antibody-based anabolic drugs that are currently being developed present the potential limits in clinical application typical of macromolecule drugs. We previously identified that CXXC5 is a negative feedback regulator of the Wnt/ß-catenin pathway via its interaction with Dishevelled (Dvl) and suggested the Dvl-CXXC5 interaction as a potential target for anabolic therapy of osteoporosis. Here, we screened small-molecule inhibitors of the Dvl-CXXC5 interaction via a newly established in vitro assay system. The screened compounds were found to activate the Wnt/ß-catenin pathway and enhance osteoblast differentiation in primary osteoblasts. The bone anabolic effects of the compounds were shown using ex vivo-cultured calvaria. Nuclear magnetic resonance (NMR) titration analysis confirmed interaction between Dvl PDZ domain and KY-02061, a representative of the screened compounds. Oral administration of KY-02327, one of 55 newly synthesized KY-02061 analogs, successfully rescued bone loss in the ovariectomized (OVX) mouse model. In conclusion, small-molecule inhibitors of the Dvl-CXXC5 interaction that block negative feedback regulation of Wnt/ß-catenin signaling are potential candidates for the development of bone anabolic anti-osteoporosis drugs.

PF-3758309, p21-activated kinase 4 inhibitor, suppresses migration and invasion of A549 human lung cancer cells via regulation of CREB, NF-κB, and ß-catenin signalings.

Migration and invasion comprise key steps in cancer metastasis. Through the migration and invasion into and out of lymphatic and/or blood vessels, cancer cells can be spread out into the tissues in remote site from the origin. Degradation of extracellular matrix (ECM) must be preceded prior to the metastasis of cancer cells. Matrix metalloproteinases (MMP) can degrade ECM, thus allow cells to migrate from the original site. Among MMPs, two gelatinase MMP-2 and MMP-9 play particularly important roles in ECM degradation. Here, we report that recently developed p21-activated kinase 4 inhibitor PF-3758309 shows anti-metastatic effect in A549 human lung cancer cell. PF-3758309 suppresses CREB, NF-κB, and ß-catenin pathways, which are well known to be closely related with cell migration. This leads to the downregulation of MMP-2/MMP-9 expressions and the inhibition of A549 lung cancer metastasis.

Synthesis of dibenzoxepine lactams via a Cu-catalyzed one-pot etherification/aldol condensation cascade reaction: application toward the total synthesis of aristoyagonine.

A general synthesis of dibenzoxepine lactams has been developed using a one-pot Cu-catalyzed etherification/aldol condensation cascade reaction. The reaction of 4-hydroxyisoindolin-1-one with a wide range of 2-bromobenzaldehydes in the presence of a copper catalyst provided various aristoyagonine derivatives in good yields.

Total synthesis of laetevirenol A.

The first complete synthesis of laetevirenol A was performed in nine steps via intramolecular Friedel-Crafts alkylation in a trans-selective manner. The key phenanthrene intermediate was synthesized by a one-pot Suzuki-Miyaura coupling and an aldol condensation cascade reaction.

One-pot transition-metal-free synthesis of dibenzo[b,f]oxepins from 2-halobenzaldehydes.

A one-pot transition-metal-free, base-mediated synthesis of dibenzo[b,f]oxepins was developed. The reaction of 2-halobenzaldehydes with (2-hydroxyphenyl)acetonitriles proceeds via a sequential aldol condensation and intramolecular ether formation reaction in the presence of Cs(2)CO(3) and molecular sieves in toluene.

Anti-androgen receptor activity of apoptotic CK2 inhibitor CX4945 in human prostate cancer LNCap cells.

Androgen receptor (AR) is crucial for transcriptional signaling in prostate cancers. The anti-cancer activity of protein kinase CK2 (formerly called casein kinase 2)-specific small molecule inhibitors have been reported in several cancers including prostate cancers. The orally available CX4945, a potent and selective small molecule inhibitor of CK2, has advanced into human clinical trials and has exhibited strong anti-tumor activity. The inhibition of CK2 leads to a down-regulation of the AR-dependent transcription, but the functional relevance of CX4945 to AR-dependent transcription in AR-positive LNCap cells has not been studied yet. Our observation of inhibitory effects of CX4945 on the expression or phosphorylation levels of CK2α, Akt and anti-apoptotic molecules including IAP family members agreed with a previous study showing the effect of CK2 inhibition in cancer cells. This study also provides novel information on the impact of CX4945 in the inhibition of AR-dependent transcriptional activation in LNCap cells via its down-regulation. Pharmacologic inhibition experiment revealed that CX4945 could exhibit its anti-cancer activity in LNCap cells via the independent inhibitions of AR and Akt-survivin signalings.

Stereoselective palladium-catalyzed α-arylation of 3-aryl-1-indanones: an asymmetric synthesis of (+)-pauciflorol F.

Highly stereoselective, palladium-catalyzed α-arylation reactions of 3-aryl-1-indanones with aryl bromides are described. The use of sodium tert-butoxide as a base in this process is required to elevate the efficiencies and stereoselectivities of these reactions. The new methodology was successfully applied to a highly efficient route for the asymmetric synthesis of (+)-pauciflorol F.

Synthesis of aristolactam analogues and evaluation of their antitumor activity.

A series of natural aristolactams and their analogues have been prepared and evaluated for antitumor activity against human cancer cells, including multi-drug resistant cell lines. Naturally occurring aristolactams, such as aristolactam BII (cepharanone B), aristolactam BIII, aristolactam FI (piperolactam A), N-methyl piperolactam A, and sauristolactam showed moderate antitumor activities in selected cell lines. However, several synthetic aristolactam derivatives exhibited potent antitumor activities against a broad array of cancer cell lines with GI(50) values in the submicromolar range.

Efficient synthesis of dibenzo[a,c]cyclohepten-5-ones via a sequential Suzuki-Miyaura coupling and aldol condensation reaction.

A common strategy for the synthesis of a 7-membered-ring system with a Suzuki-Miyaura coupling followed by an acid/base-promoted intramolecular aldol condensation reaction has been developed. The reaction of 2'-bromoacetophenones with 2-formylphenylboronic acids in the presence of Pd(OAc)(2) and CataCXium PIntB L8 efficiently provided biaryl compounds, which were transformed to a wide array of dibenzo[a,c]cyclohepten-5-ones in excellent yields by a sequential treatment with p-TsOH, followed by 10% aq NaOH.

Total synthesis of aristolactams via a one-pot suzuki-miyaura coupling/aldol condensation cascade reaction.

A direct one-pot synthesis of phenanthrene lactams, which employs a Suzuki-Miyaura coupling/aldol condensation cascade reaction of isoindolin-1-one with 2-formylphenylboronic acid, has been developed. The approach is used to efficiently produce a number of natural aristolactams, such as aristolactam BII (cepharanone B), aristolactam BIII, aristolactam FI (piperolactam A), N-methyl piperolactam A, and sauristolactam.

Direct one-pot synthesis of phenanthrenes via Suzuki-Miyaura coupling/aldol condensation cascade reaction.

We have developed an efficient cascade reaction, a Suzuki-Miyaura coupling followed by an aldol condensation, for the construction of phenanthrene derivatives using microwave irradiation. For example, the reaction of methyl 2-bromophenylacetamide with 2-formylphenylboronic acid in the presence of a palladium catalyst and a base provided a biaryl intermediate, which underwent in situ cyclization to afford the corresponding phenanthrene in high yield.

Enantio- and diastereoselective synthesis of cyclic beta-hydroxy allylsilanes via sequential aldehyde gamma-silylallylboration and ring-closing metathesis reactions.

[reaction: see text] Highly enantioenriched cyclic allylsilanes are prepared via stereoselective gamma-silylallylboration reactions of beta- or gamma-unsaturated aldehydes followed by ring-closing metathesis.

Common-intermediate strategy for synthesis of conduritols and inositols via beta-hydroxy cyclohexenylsilanes.

[reaction: see text] Syntheses of conduritols B-D and F and d-(+)-chiro- and neo-inositols from cyclohexenylsilane intermediates are described. The key cyclohexylsilane intermediates 5 and 14 were synthesized by stereoselective olefin dihydroxylation of the corresponding cyclohexenylsilanes. Selective Peterson elimination reactions and Fleming-Tamao oxidations of 5 and 14 then delivered the targeted cyclitol derivatives.