A novel PKC-ι inhibitor abrogates cell proliferation and induces apoptosis in neuroblastoma

Protein Kinase C-iota (PKC-ι), an atypical protein kinase C isoform manifests its potential as an oncogene by targeting various aspects of cancer cells such as growth, invasion and survival. PKC-ι confers resistance to drug-induced apoptosis in cancer cells. The acquisition of drug resistance is a major obstacle to good prognosis in neuroblastoma. The focus of this research was to identify the efficacy of [4-(5-amino-4-carbamoylimidazol-1-yl)-2,3-dihydroxycyclopentyl] methyl dihydrogen phosphate (ICA-1) as a novel PKC-ι inhibitor in neuroblastoma cell proliferation and apoptosis. ICA-1 specifically inhibits the activity of PKC-ι but not that of PKC-zeta (PKC-ζ), the closely related atypical PKC family member. The IC(50) for the kinase activity assay was approximately 0.1μM which is 1000 times less than that of aurothiomalate, a known PKC-ι inhibitor. Cyclin dependent kinase 7 (Cdk7) phosphorylates cyclin dependent kinases (cdks) and promotes cell proliferation. Our data shows that PKC-ι is an in vitro Cdk7 kinase and the phosphorylation of Cdk7 by PKC-ι was potently inhibited by ICA-1. Furthermore, our data shows that neuroblastoma cells proliferate via a PKC-ι/Cdk7/cdk2 cell signaling pathway and ICA-1 mediates its antiproliferative effects by inhibiting this pathway. ICA-1 (0.1μM) inhibited the in vitro proliferation of BE(2)-C neuroblastoma cells by 58% (P=0.01). Additionally, ICA-1 also induced apoptosis in neuroblastoma cells. Interestingly, ICA-1 did not affect the proliferation of normal neuronal cells suggesting its potential as chemotherapeutic with low toxicity. Hence, our results emphasize the potential of ICA-1 as a novel PKC-ι inhibitor and chemotherapeutic agent for neuroblastoma.     

Silibinin: a novel inhibitor of Aβ aggregation

Alzheimer's disease (AD) is characterized by the abnormal aggregation of amyloid β peptide (Aβ) into extracellular fibrillar deposits known as amyloid plaque. Inhibition of Aβ aggregation is therefore viewed as a potential method to halt or slow the progression of AD. It is reported that silibinin (silybin), a flavonoid derived from the herb milk thistle (Silybum marianum), attenuates cognitive deficits induced by Aβ25-35 peptide and methamphetamine. However, it remains unclear whether silibinin interacts with Aβ peptide directly and decreases Aβ peptide-induced neurotoxicity. In the present study, we identified, through employing a ThT assay and electron microscopic imaging that silibinin also appears to act as a novel inhibitor of Aβ aggregation and this effect showed dose-dependency. We also show that silibinin prevented SH-SY5Y cells from injuries caused by Aβ(1-42)-induced oxidative stress by decreasing H(2)O(2) production in Aβ(1-42)-stressed neurons. Taken together, these results indicate that silibinin may be a novel therapeutic agent for the treatment of AD.     

A novel calmodulin-β-PIX interaction and its implication in receptor tyrosine kinase regulation

Calmodulin (CaM), a ubiquitous calcium-binding protein, regulates numerous cellular processes, primarily in response to calcium flux. We have identified and characterized a novel interaction between CaM and β-p21-activated kinase interacting exchange factor (β-PIX), a putative guanine exchange factor implicated in cell signaling, using affinity pull-down assays, co-immunoprecipitation, co-localization and circular dichroism studies. Fluorescence-based titration and isothermal titration calorimetry experiments revealed a Ca(2+)-dependent binding mechanism (K(D)≤10μM). Further, we show that CaM participates in a multi-protein complex involving β-PIX and E3 ubiquitin ligase c-Cbl (casitas B-cell lymphoma), which may play a critical role in receptor tyrosine kinase regulation and downstream signaling.     

Pharmacological study of the novel compound FLZ against experimental parkinson’s models and its active mechanism

FLZ is a synthetic new derivative of squamosamide. Pharmacological study found that FLZ given orally improved the abnormal behavior caused by the functional disturbance of dopaminergic and cholinergic neurons in mice. FLZ significantly increased the content of dopamine and its metabolites in striatum in MPTP model mice. FLZ also remarkably protected dopaminergic PC-12 cells against dopamine and MPP⁺ induced injury and apoptosis in vitro. The compound inhibited the formation of dopamine-melanin and protein polymers. Additionally, FLZ inhibited cytochrome-c release from mitochondria and caspase-3 activation by dopamine in PC-12 cells. The above results suggest that compound FLZ possesses anti-PD activity through neuroprotection.     

TF — A novel cell-permeable and selective inhibitor of human protein kinase CK2 induces apoptosis in the prostate cancer cell line LNCaP

BackgroundAbnormally high activity of protein kinase CK2 is linked to various diseases including cancer. Therefore, the inhibition of CK2 is a promising therapeutic strategy to fight this disease.MethodsWe screened a library of synthetic molecules concerning their capacity to inhibit CK2. The activity of CK2 and their IC₅₀ and K_i values were determined by a capillary electrophoresis assay. The effects of the inhibitor in a cell culture model were analyzed by cell counting, a viability assay, cytofluorimetry and Western blot.ResultsThe best CK2 inhibitor found in this screen was 6,7-dichloro-1,4-dihydro-8-hydroxy-4-[(4-methylphenylamino)methylen]dibenzo [b,d]furan-3(2H)-one, which we refer to as “TF”. TF showed tight binding to CK2 with low IC₅₀ (29 nM) and K_i (15 nM) values. TF inhibited only seven out of 61 human kinases tested (> 70% inhibition). Incubation of LNCaP cells with 50 μM TF for 48 h decreased the intracellular CK2 activity by 50%, confirming that the inhibitor is membrane permeable. The decrease in activity was correlated with a severe reduction in cell viability. The reduction in cell viability is at least partly due to the induction of apoptosis.General significanceIn many cancers the protein kinase CK2 is significantly up-regulated and supports the neoplastic phenotype. New therapeutic strategies should be based on diverse reliable inhibitors to reverse the abnormal high levels to normal settings.     

Glutaraldehyde—its purity and stability

Summary Six commercially available glutaraldehydes were tested spectrophotometrically for their purity. These results were compared with glutaraldehyde purified by two experimental techniques. Ten sets of storage conditions were chosen and aliquots of purified glutaraldehyde were stored under these conditions for eight months. These samples enabled the reappearance of the main contaminant, absorbing strongly at 235 nm, to be examined with regard to temperature, light and the availability of oxygen. From the results the optimum criteria for storage of pure glutaraldehyde were elucidated. The results lend weight to the view that the main contaminent in stored glutaraldehyde is a polymer of glutaraldehyde and not glutaric acid.     

Immobilization of cellulase through its carbohydrate side chains — A rationale for its recovery and reuse

The major types of components of cellulase [see 1,4-(1, 3;1,4)-β-d-glucan 4-glucanohydrolase, EC 3.2.1.4] have been adsorbed onto concanavalin A immobilized on Sepharose 4B, suggesting that they are glycoproteins. These components were covalently coupled to cyanogen bromide-activated Sepharose after aminoalkylation of their periodate-oxidized carbohydrate side chains to provide additional points of attachment of the enzyme to the support. Although there was only a 9% recovery of starting avicelase activity, the immobilized enzyme catalysed the hydrolysis of insoluble cellulose to glucose with greater efficiency than did free cellulase.     

Pharmacophore-based discovery of a novel cytosolic phospholipase A(2)α inhibitor

The release of arachidonic acid, a precursor in the production of prostaglandins and leukotrienes, is achieved by activity of the cytosolic phospholipase A(2)α (cPLA(2)α). Signaling mediated by this class of bioactive lipids, which are collectively referred to as eicosanoids, has numerous effects in physiological and pathological processes. Herein, we report the development of a ligand-based pharmacophore model and pharmacophore-based virtual screening of the National Cancer Institute (NCI) database, leading to the identification of 4-(hexadecyloxy)-3-(2-(hydroxyimino)-3-oxobutanamido)benzoic acid (NSC 119957) as cPLA(2)α inhibitor in cell-free and cell-based in vitro assays.     

A new fla gene in Salmonella typhimurium—flaR—and its mutant phenotype-superhooks

Summary An electron microscopic examination of eight non-flagellate strains of S. typhimurium revealed that an H1 (amber) mutant produced flagellar hooks and basal structures indistinguishable from those associated with the proximal end of normal flagella. No flagella-related structures were seen in strains with mutations in fla genes A, B, C, D, F, K or M. A mutant of a new fla complementation group, flaR, produced abnormal structures, termed superhooks, which resemble the hooks of normal flagella assembled end-to-end. The mutant locus, flaR, maps between flaM and flaAIII.     

Hydrophilicity and antigenicity of proteins — A case study of myoglobin and hemoglobin

Hydrophilicity index is used to locate antigenic determinants on two related groups of proteins-myoglobin and hemoglobin. The data on 41 species (including 34 mammals) of myoglobin show that average hydrophilicity for the complete myoglobin molecules as well as the average hydrophilicity for all hydrophilic regions put together seem to remain constant; the variation in the size and location of the antigenic determinants in these species is very small indicating that the antigenic sites are not shifted during evolution. In the case of both the proteins there is a good agreement between the antigenic sites picked up by using hydrophilicity index and the experimentally determined antigenic sites. The data on 56 species of hemoglobin α-chains and 44 species of hemoglobinβ-chains showed that although there are few sites on hemoglobin which have remained invariant during evolution, there is a significant variation in other sites in terms of either a splitting of a site, or a drastic change in the hydrophilicity values and/or a length of the site. Comparison of the hydrophilicity data on these two groups of proteins suggests that hemoglobins which perform a variety of functions as compared to myoglobins are evolving faster than myoglobins supporting the contention of earlier workers.     

Synthesis and SAR study of imidazoquinolines as a novel structural class of microsomal prostaglandin E₂ synthase-1 inhibitors

The imidazoquinoline derivative 1 was found as a novel mPGES-1 inhibitor. Optimization of 1 led to the identification of the 2-chlorophenyl group at the C(2)-position and the quinolone structure at the C(4)-position. Compound 33, the most potent synthesized compound, showed excellent mPGES-1 inhibition (IC(50)=9.1nM) with high selectivity (>1000-fold) over both COX-1 and COX-2.     

A two-locus mutation—Selection model and some of its evolutionary implications

The deterministic properties of a two-locus model with mutation and selection have been investigated. The mutation process is unidirectional, and the model is so constructed that the genetic variation at one locus is selectively neutral in the absence of a mutant allele at the other locus. All genotypes with three or four mutant alleles are deleterious, while the double heterozygotes may have the same fitness as the standard genotype. If one of the mutant alleles becomes fixed in the population, then the other locus will show a regular one-locus mutation-selection balance. Such a boundary equilibrium may be unstable or stable in the full two-locus setting. In the symmetric case, which is analyzed in details, the population will either go to one of the two boundary equilibria, or to a fully polymorphic equilibrium at which both the mutant alleles are rare. The origin of reproductive separation between two populations via the fixation of complementary deleterious mutants at different loci, and the fixation of nonfunctional alleles at duplicated loci, are two biological processes which both can be studied with the present model. In the last part of the paper we show how the results from the deterministic analysis can be used to predict how different factors will influence the rates of evolution in these systems.     

Synthesis of novel disulfide and sulfone hybrid scaffolds as potent β-glucuronidase inhibitor

Novel series of disulfide and sulfone hybrid analogs (1 −2 0) were synthesized and characterized through EI-MS and ¹H NMR and evaluated for β-glucuronidase inhibitory potential. All synthesized analogs except 13 and 15 showed excellent β-glucuronidase inhibitory potential with IC₅₀ value ranging in between 2.20–88.16 μM as compared to standard d-saccharic acid 1,4 lactone (48.4 ± 1.25 μM). Analogs 19, 16, 4, 1, 17, 6, 10, 3, 18, 2, 11, 14 and 5 showed many fold potent activity against β-glucuronidase inhibitor. Structure activity relationship showed that substitution of electron withdrawing groups at ortho as well as para position on phenyl ring increase potency. Electron withdrawing groups at meta position on phenyl ring showed slightly low potency as compared to ortho and para position. The binding interactions were confirmed through molecular docking studies.     

A novel fire danger rating model based on time fading precipitation model — A case study of Northeast China

With the increase of extreme climate and global warming, forest fires have become more frequent. Therefore, it is important to accurately predict whether fires will occur in forest in the future. Precipitation is an important factor that affects the probability of the occurrence of forest fires in the future. Previous models selected annual average precipitation, monthly average precipitation or drought days as the precipitation value, which the attenuation of precipitation is not considered. In this study, a time fading model is used to calculate the comprehensive precipitation index, which is an exponential weight decay model. The earlier the precipitation time, the smaller the weight. This method can better represent the effect of precipitation in predicting the occurrence of forest fires. Moreover, in this study, discrete fire points are converted into a continuous fire-point density. The structure of the prediction model is more reasonable, which is conducive to obtaining higher-precision prediction results. Besides, the SVM regression model was used to construct a forest fire danger rating model. In the same area, considering the comprehensive precipitation index compared with the average precipitation value, the accuracy of the three forest areas in northeastern China in the test set has been improved by about 5%. The accuracy rates of 90.13%, 93.04% and 87.5% can be achieved respectively.