Nizofenone, a neuroprotective drug, suppresses glutamate release and lactate accumulation

Discovery of a New CDK4/6 and PI3K/AKT Multiple Kinase Inhibitor Aminoquinol for the Treatment of Hepatocellular Carcinoma

Background: Hepatocellular carcinoma (HCC) is a lethal malignancy lacking effective treatment. The Cyclin-dependent kinases 4/6 (CDK4/6) and PI3K/AKT signal pathways play pivotal roles in carcinogenesis and are promising therapeutic targets for HCC. Here we identified a new CDK4/6 and PI3K/AKT multi-kinase inhibitor for the treatment of HCC. Methods: Using a repurposing and ensemble docking methodology, we screened a library of worldwide approved drugs to identify candidate CDK4/6 inhibitors. By MTT, apoptosis, and flow cytometry analysis, we investigated the effects of candidate drug in reducing cell-viability,inducing apoptosis, and causing cell-cycle arrest. The drug combination and thermal proteomic profiling (TPP) method were used to investigate whether the candidate drug produced antagonistic effect. The in vivo anti-cancer effect was performed in BALB/C nude mice subcutaneously xenografted with Huh7 cells. Results: We demonstrated for the first time that the anti-plasmodium drug aminoquinol is a new CDK4/6 and PI3K/AKT inhibitor. Aminoquinol significantly decreased cell viability, induced apoptosis, increased the percentage of cells in G1 phase. Drug combination screening indicated that aminoquinol could produce antagonistic effect with the PI3K inhibitor LY294002. TPP analysis confirmed that aminoquinol significantly stabilized CDK4, CDK6, PI3K and AKT proteins. Finally, in vivo study in Huh7 cells xenografted nude mice demonstrated that aminoquinol exhibited strong anti-tumor activity, comparable to that of the leading cancer drug 5-fluorouracil with the combination treatment showed the highest therapeutic effect. Conclusion: The present study indicates for the first time the discovery of a new CDK4/6 and PI3K/AKT multi-kinase inhibitor aminoquinol. It could be used alone or as a combination therapeutic strategy for the treatment of HCC.

Pharmacological evidence for a correlation between hippocampal CA1 cell damage and hyperlocomotion following global cerebral ischemia in gerbils

Global ischemia, induced in Mongolian gerbils by bilateral occlusion of the carotid arteries for 5 min, produced a significant increase in locomotor activity at 1 day post-occlusion and a severe loss of hippocampal CA1 neurons at 4 days post-occlusion. To explore the pharmacological relationship between ischemia-induced hypermotility and CA1 cell death in the hippocampus, we evaluated the efficacy of diverse classes of putative neuroprotective agents for preventing hypermotility and delayed neuronal death. Administration of any drug 30 min before global ischemia dose-dependently, and with similar potency, ameliorated both hippocampal delayed neuronal death and locomotor hyperactivity, with a rank order: tacrolimus (FK506)>nizofenone>clonindine>dizocilpine (MK-801)>6-(1H-imidazol-1-yl)-7-nitro-2,3(1H,4H)-quinoxalinedione hydrochloride (YM90K)>phencyclidine>pentobarbital>2-(4-(p-fluorobenzoyl)-piperidin-1-yl)-2'-acetonaphthone hydrochloride (E-2001)>cis-(+/-)-4-phosphonomethyl-2-piperidine carboxylic acid (CGS19755)>3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]benzeneacetamide (U-50,488H)>piroxicam>eliprodil>vinpocetine. Furthermore, potencies of the protective effect on delayed neuronal death and inhibitory effects on hypermotility were closely correlated (r=0.98). These results suggest that post-ischemic CA1 injury and hypermotility share common mechanisms, and further imply that it is possible to predict the neuroprotective efficacy of drugs more easily by examining the inhibitory effects on post-ischemic hypermotility in global ischemia model in gerbils.

Effects of ibudilast on hippocampal long-term potentiation and passive avoidance responses in rats with transient cerebral ischemia

The present study evaluated the effects of ibudilast on impaired passive avoidance responses and hippocampal long-term potentiation (LTP) caused by transient cerebral ischemia in rats. The hippocampal nerve cell density was also measured. The latency determined in retention trials of passive avoidance shortened significantly in the 4-vessel occlusion (4VO) group (in which four blood vessels were occluded for 20 min to cause cerebral ischemia). A significant recovery in the latency was observed by administration of ibudilast (10 mg kg (-1)). The population spike amplitude in both the hippocampal CA1 region and perforant path-dentate gyrus synapses was potentiated by tetanus stimulation in the sham-operated group, while in the 4VO group, LTP was significantly inhibited. This inhibition was reversed by administration of ibudilast (10 mg kg (-1)). A marked reduction of cell densities in the CA1 region was observed in the 4VO group compared with the normal group. The nerve cell density in the hippocampal CA1 region was decreased by 20 min of cerebral ischemia. Ibudilast significantly inhibited the reduction of cell densities in a dose-dependent manner. In contrast, the cell density in the dentate gyrus was comparable in the 4VO and normal groups, and no significant changes were observed in the ibudilast groups. These findings suggest that ibudilast might possess neuronally protective properties, i.e. protecting neurons not only from deaths but also from functional damage due to certain cerebral ischemia.

Monitoring of extracellular pyruvate, lactate, and ascorbic acid during cerebral ischemia: a microdialysis study in awake gerbils

In vivo microdialysis coupled with liquid chromatography was developed for the continuous monitoring of brain neurochemicals during cerebral ischemia in awake, free moving gerbils. The dead volume of the microdialysis system was estimated to be less than 30 microl. The detection limits of the present assay were 0.2 to 2.0 microM for analytes at a signal to noise ratio of five. To validate this assay, a focal cerebral ischemia was produced by occlusion of one common carotid artery for 60 min and then reperfusion for additional 3 h in awake gerbils. A microdialysis probe was inserted into the striatum of the gerbil. Dialysates were autoinjected and analyzed extracellular pyruvate, lactate, and ascorbic acid by liquid chromatography with a UV detector during cerebral ischemia. Significant changes of pyruvate and the lactate/pyruvate ratio were observed. Biphasic and dynamic changes in ascorbic acid and lactate were proposed to correlate a secondary damage. This assay can be used as a tool to study dynamic changes of brain neurochemicals in awake animals.

Lactic acid-induced increase of extracellular dopamine measured by microdialysis in rat striatum: evidence for glutamatergic and oxidative mechanisms

Striatal lactacidosis was induced by direct lactic acid perfusion to obtain a local pH as close as possible to that observed in ischemia. In a previous study we showed that such lactacidosis produces a diphasic increase in extracellular dopamine (DA). The present work investigated whether DA accumulation is related to a glutamatergic mechanism and/or production of reactive oxygen species (ROS) in the striatum. Concentrations of extracellular DA, glutamate and hydroxyl radicals ((.)OH) were measured in the presence or absence of an N-methyl-D-aspartate (NMDA) receptor blocker (dizocilpine, MK-801) or an antioxidant (Trolox). Measurements were performed using high-performance liquid chromatography (HPLC) with electrochemical and fluorimetric detection on samples obtained by an in vivo microdialysis perfusion technique and stored at -80 degrees C. The increase in lactic acid-induced DA was entirely suppressed by MK-801 and Trolox. Lactacidosis also induced an increase in extracellular glutamate and (.)OH concentrations at the same time as the first DA accumulation, as well as another (.)OH accumulation which preceded and accompanied the second DA concentration peak. Glutamate release was totally inhibited by MK-801 or Trolox. The first peak of (.)OH production was completely suppressed by MK-801 and Trolox, but the second one was only suppressed by Trolox. These data showed that the increase in DA induced by lactic acid was related to glutamatergic excitotoxicity and ROS production, suggested that the kinetic of events was different for the two DA accumulations.

Changes in excitatory amino acid levels and tissue energy metabolites of neonate rat brain after hypoxia and hypoxia-ischemia

Lactate accumulation, amino acid aspartate and glutamate levels, and hypoxanthine, xanthine and malondialdehyde (MDA) concentrations were compared in neonate rat brain after transient global hypoxia induced alone or in association with unilateral ligation of a carotid artery. Lactate production in both hemispheres was higher in cerebral hypoxia-ischemia (CHI) than in cerebral hypoxia (CH), and was lower in CHI after 2 h than at 15 min of recovery. Aspartate and glutamate levels were reduced 15 min after CHI in both hemispheres, but aspartate alone was decreased 2 h after CHI in the ipsilateral (left) hemisphere and 15 min after CH in both hemispheres. Hypoxanthine was increased 15 min after CHI in the ipsilateral hemisphere but decreased at 2 h, whereas xanthine was increased. MDA production was not modified after CH or CHI. These data, compared to those obtained in adult animals suggest that glutamate release and the capacity to generate oxygen-derived radicals are lower in neonates after ischemia. These differences might explain why the brain of the mammalian neonate is much more resistant to CH and CHI than that of the adult.

Volume-sensitive chloride channels blocked by neuroprotective drugs in human glial cells (U-138MG)

Glial cell swelling in hypotonic media activates an anionic channel that was found previously to be permeable to amino acids. It is possible that the same channel is also activated when glial cells swell in pathologic conditions, like ischemia or hypoxia, and it could be partly responsible for the release of glutamate appearing in such conditions. Many drugs have been developed to block glutamate release during ischemia. Six of these drugs were tested on human glial cells (U-138MG) in vitro to determine if they could block the swelling-activated anionic channels. Three of them, phenytoin, lidocaine, and flunarizine, had no effect. The other three could block the anionic channels: riluzole, nizofenone, and BW1003C87. Such blocking was reversible and the half inhibition concentration (IC50) of each of these drugs was within that observed for their inhibition of glutamate release by various authors. An important advantage of these three drugs is their capacity to inhibit glutamate release after the beginning of ischemia. It is concluded that the volume-sensitive anionic channel could be partly responsible for glutamate release during a cerebral ischemia.