Magnolin inhibits cell migration and invasion by targeting the ERKs/RSK2 signaling pathway.

BACKGROUND: Magnolin is a natural compound abundantly found in Magnolia flos, which has been traditionally used in oriental medicine to treat headaches, nasal congestion and anti-inflammatory reactions. Our recent results have demonstrated that magnolin targets the active pockets of ERK1 and ERK2, which are important signaling molecules in cancer cell metastasis. The aim of this study is to evaluate the effects of magnolin on cell migration and to further explore the molecular mechanisms involved. METHODS: Magnolin-mediated signaling inhibition was confirmed by Western blotting using RSK2(+/+) and RSK2(-/-) MEFs, A549 and NCI-H1975 lung cancer cells, and by NF-κB and Cox-2 promoter luciferase reporter assays. Inhibition of cell migration by magnolin was examined by wound healing and/or Boyden Chamber assays using JB6 Cl41 and A549 human lung cancer cells. The molecular mechanisms involved in cell migration and epithelial-to-mesenchymal transition were determined by zymography, Western blotting, real-time PCR and immunocytofluorescence. RESULTS: Magnolin inhibited NF-κB transactivation activity by suppressing the ERKs/RSK2 signaling pathway. Moreover, magnolin abrogated the increase in EGF-induced COX-2 protein levels and wound healing. In human lung cancer cells such as A549 and NCI-H1975, which harbor constitutive active Ras and EGFR mutants, respectively, magnolin suppressed wound healing and cell invasion as seen by a Boyden chamber assay. In addition, it was observed that magnolin inhibited MMP-2 and -9 gene expression and activity. The knockdown or knockout of RSK2 in A549 lung cancer cells or MEFs revealed that magnolin targeting ERKs/RSK2 signaling suppressed epithelial-to-mesenchymal transition by modulating EMT marker proteins such as N-cadherin, E-cadherin, Snail, Vimentin and MMPs. CONCLUSIONS: These results demonstrate that magnolin inhibits cell migration and invasion by targeting the ERKs/RSK2 signaling pathway.

Aschantin targeting on the kinase domain of mammalian target of rapamycin suppresses epidermal growth factor-induced neoplastic cell transformation.

Mammalian target of rapamycin (mTOR), a serine/threonine protein kinase, forms two different complexes, complex 1 and 2, and plays a key role in the regulation of Akt signaling-mediated cell proliferation and transformation. This study reveals aschantin, a natural compound abundantly found in Magnolia flos, as a novel mTOR kinase inhibitor. Aschantin directly targeted the active pocket of mTOR kinase domain by competing with adenosine triphosphate (ATP), but not PI3K and PDK1. Aschantin inhibited epidermal growth factor (EGF)-induced full activation of Akt by phosphorylation at Ser473/Thr308, resulting in inhibition of the mTORC2/Akt and Akt/mTORC1/p70S6K signaling pathways and activation of GSK3ß by abrogation of Akt-mediated GSK3ß phosphorylation at Ser9. The activated GSK3ß inhibited cell proliferation by c-Jun phosphorylation at Ser243, which facilitated destabilization and degradation of c-Jun through the ubiquitination-mediated proteasomal degradation pathway. Notably, aschantin treatment decreased c-Jun stability through inhibition of the mTORC2-Akt signaling pathway, which suppressed EGF-induced anchorage-independent cell transformation in non-malignant JB6 Cl41 and HaCaT cells and colony growth of LNCaP and MIAPaCa-2 cancer cells in soft agar. Altogether, the results show that aschantin targets mTOR kinase and destabilizes c-Jun, which implicate aschantin as a potential chemopreventive or therapeutic agent.

Synthesis and antibacterial activities of new piperidine substituted (5R)-[1,2,3]triazolylmethyl and (5R)-[(4-F-[1,2,3]triazolyl)methyl] oxazolidinones.

A novel series of 5(R)-[1,2,3]triazolylmethyl and (5R)-[(4-F-[1,2,3]triazolyl)methyl]oxazolidinones having various piperidine group were synthesized and evaluated antibacterial activity against clinically isolated resistant strains of Gram-positive and Gram-negative bacteria. The compound 12a having exo-cyanoethylidene group in the 4-position of piperidine ring was found to be two to threefold more potent than the linezolid against penicillin-resistant Staphylococcus pneumonia and Staphylococcus agalactiae, and also exhibited reduced MAO-B inhibitory activity.

Synthesis and antibacterial activity of new 9-O-arylpropenyloxime ketolides.

A novel series of 9-O-arylpropenyloxime ketolide was synthesized and evaluated for their antibacterial activity. This series of ketolide exhibited potent activity against clinically isolated gram-positive strains including Staphylococcus pneumoniae and Straptococcus Pyogenes.

Novel 6-N-arylcarboxamidopyrazolo[4,3-d]pyrimidin-7-one derivatives as potential anti-cancer agents.

A novel series of 3,5,6-trisubstituted pyrazolo[4,3-d]pyrimidin-7-one derivatives, especially 6-N-arylcarboxamidopyrazolo[4,3-d]pyrimidin-7-ones were synthesized and evaluated for their in vitro anticancer activities against various human cancer cell lines. The inhibitory activities for several kinases have also been tested. The prepared compounds library exhibited significant anticancer activity towards HT-29 colon and DU-145 prostate cancer cell lines. The structure-activity relationships of the 6-N-arylcarboxamidopyrazolo[4,3-d]pyrimidin-7-one scaffold at R(1), R(2) and R(3) have been elucidated. Among the synthesized compounds, 12b was the most active compound with GI(50) value of 0.44microM and 1.07microM against HT-29 and DU-145 cell lines, respectively, and 13a was the most selective compound towards colon cancer cell line.

5-Exocyclic products, 2,3,5-trisubstituted tetrahydrofurans via Prins-type cyclization.

[reaction: see text] 5-Exocyclic products, 2,3,5-trisubstituted tetrahydrofurans, were synthesized from homopropargylic alcohols with terminally substituted alkynes and various aldehydes via Prins-type cyclization. It is of interest that the exocyclic vinyl cation generated as a result of Prins-type cyclization could be trapped as a vinyl triflate when CH2Cl2 was used as a solvent, whereas in ethereal solution the vinyl cation underwent hydrolysis to give the corresponding ketone product.

Identification of compounds that inhibit the interaction between core and surface protein of hepatitis B virus.

Specific interactions of the human hepatitis B virus (HBV) surface proteins with the core protein of nucleocapsid are critical for the envelopment of virus particles, and inhibition of this process may prevent the production of infectious virus. A modified enzyme-linked immunosorbent assay (ELISA), which measured the interaction between the core protein and PreS region of the surface protein, was used to screen a chemical library for compounds that would block this interaction. Few inhibitory compounds were identified from a chemical library consisting of 5600 compounds. Among them, two compounds inhibited the production of HBV particles from transiently HBV-producing HuH7 cells. The IC50 values of these compounds for inhibition of HBV production in HuH7 cells were in the micromolar concentration range. These results indicate that compounds that prevent the interaction between the core protein and PreS region of the surface protein may possibly be useful as anti-HBV agents.

Design, synthesis, and anti-Helicobacter pylori activity of erythromycin A (E)-9-oxime ether derivatives.

The synthesis and anti-Helicobacter pylori (H. pylori) activity evaluation of a new series of erythromycin A (E)-9-oxime ether derivatives are described. These compounds exhibited comparable in vitro anti-H. pylori activity and improved acid stability compared to the reference compound clarithromycin.

KKHA-761, a potent D3 receptor antagonist with high 5-HT1A receptor affinity, exhibits antipsychotic properties in animal models of schizophrenia.

KKHA-761, 1-{4-[3-(3,4-dimethoxy-phenyl)-isoxazol-5-yl]-butyl}-4-(2-methoxy-phenyl)-piperazine, has a high affinity (Ki=3.85 nM) for human dopamine D3 receptor with about 70-fold selectivity over the human dopamine D(2L) receptor (Ki=270 nM). KKHA-761 also showed high affinity for cloned human 5-HT1A receptor (Ki=6.4 nM). KKHA-761 exhibited D3 and 5-HT1A receptor antagonist activities in vitro, reversing dopamine- or 5-HT-mediated stimulation of [35S]GTPrS binding. The in vivo pharmacological profile of KKHA-761 was compared with both typical and atypical antipsychotics including clozapine and haloperidol. Apomorphine-induced dopaminergic behavior, cage climbing, in mice was potently blocked by a single administration (i.p.) of KKHA-761 (ID50=4.06 mg/kg) or clozapine (ID50=4.0 mg/kg). Cocaine- or MK-801-induced hyperactivity in animals was markedly inhibited by KKHA-761 or clozapine. In addition, KKHA-761 significantly reversed the disruption of prepulse inhibition (PPI) produced by apomorphine in mice, indicating the antidopaminergic or antipsychotic activity of KKHA-761 in mice. However, KKHA-761 was inactive in the forced swimming behavioral despair model in mice, suggesting lack of antidepressant properties. KKHA-761 attenuated the hypothermia induced by a selective dopamine D3 agonist, 7-OH-DPAT, in mice, whereas clozapine enhanced it. Moderate doses of both KKHA-761 and clozapine did not increase serum prolactin levels in rats. Lower doses of, however, haloperidol significantly increased prolactin secretion. KKHA-761 did not induce cataleptic response up to 20 mg/kg, but significant catalepsy was shown at lower doses of clozapine and haloperidol. Furthermore, KKHA-761 showed a low incidence of rotarod ataxia (TD50=34.4 mg/kg, i.p.) in mice. The present results, therefore, suggest that KKHA-761 is a potent antipsychotic agent with combined dopamine D3 and serotonin 5-HT1A receptors modulation activity, which may further enhance its therapeutic potential for anxiety, psychotic depression, and other related disorders.

The effects of subunit composition on the inhibition of nicotinic receptors by the amphipathic blocker 2,2,6,6-tetramethylpiperidin-4-yl heptanoate.

The therapeutic targeting of nicotinic receptors in the brain will benefit from the identification of drugs that may be selective for their ability to activate or inhibit a limited range of nicotine acetylcholine receptor subtypes. In the present study, we describe the effects of 2,2,6,6-tetramethylpiperidin-4-yl heptanoate (TMPH), a novel compound that is a potent inhibitor of neuronal nicotinic receptors. Evaluation of nicotinic acetylcholine receptor (nAChR) subunits expressed in Xenopus laevis oocytes indicated that TMPH can produce a potent and long-lasting inhibition of neuronal nAChR formed by the pairwise combination of the most abundant neuronal alpha (i.e., alpha3 and alpha4) and beta subunits (beta2 and beta4), with relatively little effect, because of rapid reversibility of inhibition, on muscle-type (alpha1beta1gammadelta) or alpha7 receptors. However, the inhibition of neuronal beta subunit-containing receptors was also decreased if any of the nonessential subunits alpha5, alpha6, or beta3 were coexpressed. This decrease in inhibition is shown to be associated with a single amino acid present in the second transmembrane domain of these subunits. Our data indicate great potential utility for TMPH to help relate the diverse central nervous system effects to specific nAChR subtypes.

Hologram quantitative structure activity relationship studies on 5-HT6 antagonists.

Predictive hologram quantitative structure activity relationship (HQSAR) models were developed for a series of arylsulfonamide compounds acting as specific 5-HT6 antagonists. A training set containing 48 compounds served to establish the model. The best HQSAR model was generated using atoms, bond, and connectivity as fragment distinction and 4-7 as fragment size showing cross-validated r2(q2) value of 0.702 and conventional r2 value of 0.971. The predictive ability of the model was validated by an external test set of 20 compounds giving satisfactory predictive r2 value of 0.678. The efficiency of HQSAR approach was further evidenced by the generation of predictive models for a training set containing 30 highly diverse, both specific and nonspecific 5-HT6 antagonists. The best HQSAR model for this training set was generated using atoms, bond, and connectivity as fragment distinction and 4-7 as fragment size showing cross-validated r2(q2) value of 0.693 and conventional r2 value of 0.923. This model was also validated by using an external test set of 10 compounds giving satisfactory predictive r2 value of 0.692. The contribution maps obtained from these models were used to explain the individual atomic contributions to the overall activity.

Pharmacological actions of a novel and selective dopamine D3 receptor antagonist, KCH-1110.

1-(2-ethoxy-phenyl)-4-[3-(3-thiophen-2-yl-isoxazolin-5-yl)-propyl]-piperazine (KCH-1110), has a high affinity for human dopamine D3 (hD3) receptor (Ki=1.28 nM) with about 90-fold selectivity over the human dopamine D2L (hD2L) receptor. Antipsychotic or antidopaminergic activity of KCH-1110 was investigated in the models for the positive symptoms of schizophrenia, apomorphine-induced climbing and cocaine-induced hyperlocomotion, in mice. Intraperitoneal (i.p.) or oral (p.o.) administration of KCH-1110 potently inhibited the apomorphine-induced cage climbing without any rotarod ataxia in mice. Cocaine-induced hyperactivity was also antagonised by KCH-1110. In addition, KCH-1110 attenuated the hypothermia induced by a selective dopamine D3 agonist, 7-OH-DPAT in mice. KCH-1110 did not induce catalepsy in mice, but at much higher doses only a slight catalepsy response was shown. Although high doses of KCH-1110 significantly enhanced serum prolactin secretion in rats, low dose of KCH-1110 did not increase prolactin levels in rats. The present studies, therefore, suggest that KCH-1110 is a potent and relatively selective dopamine D3 receptor antagonist with antipsychotic actions.

QSAR studies on piperazinylalkylisoxazole analogues selectively acting on dopamine D3 receptor by HQSAR and CoMFA.

QSAR studies for piperazinylalkylisoxazole analogues were conducted by hologram QSAR (HQSAR) and comparative molecular field analysis (CoMFA) to explain the binding affinities of 264 ligands acting on dopamine D(3) receptor. The HQSAR was assessed by r(2) value of 0.917 and cross validated q(2) value of 0.841. In the CoMFA, r(2) is 0.919 and cross validated q(2) is 0.727. The results provide the tools for predicting the affinity of related compounds and guiding the design of new ligands.