- SIRT2 mediated antitumour effects of shikonin on metastatic colorectal cancer. [Journal Article]
- EJEur J Pharmacol 2017 Jan 11
- SIRT2 is involved in the development of a variety of cancers. Shikonin is a natural compound that is known to have antitumour effects. This study aims to assess the effects of shikonin on the develop...
SIRT2 is involved in the development of a variety of cancers. Shikonin is a natural compound that is known to have antitumour effects. This study aims to assess the effects of shikonin on the development and metastatic progression of colorectal cancer (CRC) through regulation of SIRT2 expression and whether this effect is related to the phosphorylation of extracellular signal-regulated kinases (ERKs). The results demonstrated that SIRT2 is downregulated in CRC biopsy samples (n = 31) compared with the adjacent non-cancerous tissues (ANCT, n = 26). Furthermore, CRC metastases were positive for SIRT2 despite a lack of expression in the primary tumour. In addition, data from an in vitro assay revealed that overexpression of SIRT2 inhibited the proliferation and metastatic progression of SW480 cells while blocking of SIRT2 expression induced the proliferation and metastatic progression of HT29 cells. Shikonin inhibited the viability, migration and invasion of SW480 cells and it also inhibited the tumor growth in the nude mice model; while AGK2 (a specific inhibitor of SIRT2) reversed these effects. Epidermal growth factor (EGF, an activator of ERK) and ERK-overexpression inhibited the effects of shikonin on SIRT2 expression, proliferation and metastasis in SW480 cells. However, this proliferative effect of EGF was reversed by SIRT2 overexpression. In conclusion, these results suggest that SIRT2 is a new therapeutic target for the treatment of CRC. The antitumour effects of shikonin on CRC seem to be mediated by SIRT2 upregulation via phospho-ERK inhibition.
- Trypsin induces biphasic muscle contraction and relaxation via transient receptor potential vanilloid 1 and neurokinin receptors 1/2 in porcine esophageal body. [Journal Article]
- EJEur J Pharmacol 2017 Jan 11
- Duodenal reflux of fluids containing trypsin relates to refractory gastroesophageal reflux disease (GERD). Esophageal peristalsis and clearance are important factors in GERD pathogenesis. However, th...
Duodenal reflux of fluids containing trypsin relates to refractory gastroesophageal reflux disease (GERD). Esophageal peristalsis and clearance are important factors in GERD pathogenesis. However, the function of trypsin in esophageal body contractility is not fully understood. In this study, effects of trypsin on circular smooth muscle (CSM) and longitudinal smooth muscle (LSM) of the porcine esophageal body were examined. Trypsin elicited a concentration dependent biphasic response, a major contraction and a subsequent relaxation only in CSM. In CSM, contraction occurred at trypsin concentrations of 100nM and relaxation at 1 μM. A proteinase-activated receptor (PAR)2 activating peptide, SLIGKV-NH2 (1mM), induced a monophasic contraction. Those responses were unaffected by tetrodotoxin though abolished by the gap junction uncouplers carbenoxolone and octanol. They were also partially inhibited by a transient receptor potential vanilloid type 1 (TRPV1) antagonist and abolished by combination of neurokinin receptor 1 (NK1) and NK2 antagonists, but not by an NK3 antagonist, suggesting a PAR2-TRPV1-substance P pathway in sensory neurons. Substance P (100nM), an agonist for various NK receptors (NK1, NK2 and NK3) with differing affinities, induced significant contraction in CSM, but not in LSM. The contraction was also blocked by the combination of NK1 and NK2 antagonists, but not by the NK3 antagonist. Moreover, substance P-induced contractions were unaffected by the TRPV1 antagonist, but inhibited by a gap junction uncoupler. In conclusion, trypsin induced a biphasic response only in CSM and this was mediated by PAR2, TRPV1 and NK1/2. Gap junctions were indispensable in this tachykinin-induced response.
- Flavonoid derivative (Fla-CN) inhibited adipocyte differentiation via activating AMPK and up-regulating microRNA-27 in 3T3-L1 cells. [Journal Article]
- EJEur J Pharmacol 2017 Jan 11
- Fla-CN (3-O-[(E)-4-(4-cyanophenyl)-2-oxobut-3-en-1-yl] kaempferol) is a semi-synthesized flavonoid derivative of tiliroside which exhibited anti-diabetic effect in vivo. Our previous study revealed t...
Fla-CN (3-O-[(E)-4-(4-cyanophenyl)-2-oxobut-3-en-1-yl] kaempferol) is a semi-synthesized flavonoid derivative of tiliroside which exhibited anti-diabetic effect in vivo. Our previous study revealed the role of Fla-CN in anti-obesity and anti-diabetes in vivo, but the underlying mechanism remained to be addressed. The present study aimed to investigate the mechanism of anti-adipogenesis in vitro. Fla-CN markedly inhibited intracellular lipid accumulation in a dose-dependent manner, and the inhibitory effect was mainly limited to the early stage of adipocyte differentiation in vitro. Further investigations revealed that Fla-CN up-regulated the expression level of miR-27a/b and suppressed its target genes expression including peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα). Furthermore, the phosphorylation of AMP-activated protein kinase (AMPK) was also enhanced by Fla-CN in pre-adipocyte differentiation. These effects were abolished when cells were treated with miR-27a/b inhibitor and AMPK inhibitor Compound C. Additionally, Fla-CN reduced the expressions of adipocyte-specific genes such as sterol regulatory element-binding transcription factor 1c (SREBP-1c), fatty acid synthase (FAS) and adipocyte fatty acid binding protein (aP2). In conclusion, these results suggested a mechanism of Fla-CN for adipocyte differentiation inhibition of 3T3-L1 cells through miR-27a/b induction and AMPK activation.
- The signalling mechanisms of a novel mitochondrial complex I inhibitor prevent lipid accumulation and attenuate TNF-α-induced insulin resistance in vitro. [Journal Article]
- EJEur J Pharmacol 2017 Jan 11
- RTC-1 has recently been identified as a member of a new class of anti-diabetic compounds acting through the inhibition of complex I of the mitochondrial respiratory chain (NADH:ubiquinone oxidoreduct...
RTC-1 has recently been identified as a member of a new class of anti-diabetic compounds acting through the inhibition of complex I of the mitochondrial respiratory chain (NADH:ubiquinone oxidoreductase) to improve glucose handling and inhibit weight gain in mice fed a high-fat diet (HFD). The exact mechanism by which the reduced activity of NADH:ubiquinone oxidoreductase, in response to RTC-1, promotes these improved metabolic parameters remains to be established. Through extensive in vitro analysis, new molecular insights into these downstream signalling pathways have been obtained. RTC-1-induced inhibition of NADH:ubiquinone oxidoreductase was found to promote glucose uptake in C2C12 myotubes in vitro, through the activation of the Akt substrate of 160kDa (AS160), in response to the increased activity of Akt and AMP-activated protein kinase (AMPK). RTC-1-induced phosphorylation of the AMPK substrate, acetyl-CoA carboxylase (ACC) in vitro, was associated with a decrease in lipid accumulation in 3T3-L1 adipocytes and murine mesenchymal stromal cells (MSC). The novel compound also prevented tumour necrosis factor-alpha (TNF-α)-induced insulin resistance and demonstrated insulin sensitising effects in C2C12 myotubes. Taken together, these results present a systematic analysis of the signalling mechanisms responsible for the potent anti-diabetic and anti-obesogenic effects of this modulator of mitochondrial function, strengthening the potential use of such compounds for the treatment of type 2 diabetes mellitus (T2DM).
- Evaluating the role of astrocytes on β-estradiol effect on seizures of Pilocarpine epileptic model. [Journal Article]
- EJEur J Pharmacol 2017 Jan 11
- Epilepsy with periodic and unpredictable seizures is associated with hippocampal glutamate toxicity and tissue reorganization. Astrocytes play an important role in mediating the neuroprotective effec...
Epilepsy with periodic and unpredictable seizures is associated with hippocampal glutamate toxicity and tissue reorganization. Astrocytes play an important role in mediating the neuroprotective effects of estradiol and reducing seizure severity. Accordingly, the protective effects of low and high doses of estradiol on behavioral, astrocytic involvement and neuronal survival aspects of Pilocarpine-induced epilepsy were investigated. Lithium- Pilocarpine (30mg/kg) model was used to provoke epilepsy. Βeta-estradiol (2,40μg/ µl) was injected subcutaneously from 48 before to 48h after seizure induction. Behavioral convulsions were then monitored and recorded on the day of induction. Four weeks later, glutamine synthetase (GS) activity and the astrocyte transporter GLT-1 expression of the hippocampus were measured. Moreover, hippocampal glutamate and GABA were evaluated to study excitability changes. Finally, neuronal counting in the hippocampus was also performed using Nissl staining. The latency for generalized clonic (GC) convulsions significantly increased while the rate of GC and death significantly reduced due to β-estradiol treatment. GS activity and GLT-1 expression increased in the groups receiving the high dose of β-estradiol and Pilocarpine. Furthermore, the amount of both GABA and glutamate content decreased due to high dose of estradiol, while only GABA increased in Pilocarpine treated rats. Finally, administration of β-estradiol with low and high doses increased and improved the density of nerve cells. It is concluded that chronic administration β-estradiol has anticonvulsant and neuroprotective properties which are plausibly linked to astrocytic activity.
- Unknown face of known drugs - what else can we expect from angiotensin converting enzyme inhibitors? [Review]
- EJEur J Pharmacol 2017 Jan 10
- The renin-angiotensin system (RAS) is one of important systems among homeostatic mechanisms that controls the function of cardiovascular, renal and adrenal systems. As RAS has a very complex nature, ...
The renin-angiotensin system (RAS) is one of important systems among homeostatic mechanisms that controls the function of cardiovascular, renal and adrenal systems. As RAS has a very complex nature, it has been also found as related to the control of cell migration and apoptosis. Angiotensin-converting enzyme inhibitors (ACEI) are drugs most commonly used in the modulation of RAS activity. ACEI have been extensively described as effective in the treatment of hypertension among adults, but also as drugs delaying progression in diabetic nephropathy and reducing mortality in left ventricular dysfunction and congestive heart failure. What is less obvious, ACEI are also widely used in pediatric nephrology and cardiology. Moreover, there are more and more reports showing evidence that ACEI can be beneficial in the treatment of many other diseases and the pleiotropic activity of ACEI is mainly based on their antioxidant properties. In this paper we focus on the less obvious possibilities of the clinical use of ACEI in neurological or oncological patients, discuss the role of ACE gene polymorphism and show the perspectives of potentially new applications of ACEI in contemporary pharmacotherapy.
- Anti-diabetic drug metformin dilates retinal blood vessels through activation of AMP-activated protein kinase in rats. [Journal Article]
- EJEur J Pharmacol 2017 Jan 10
- The aim of this study was to examine whether metformin, a biguanide anti-hyperglycemic drug, dilates retinal blood vessels in rats. Ocular fundus images were captured with an original high-resolution...
The aim of this study was to examine whether metformin, a biguanide anti-hyperglycemic drug, dilates retinal blood vessels in rats. Ocular fundus images were captured with an original high-resolution digital fundus camera in vivo and diameters of retinal blood vessels were measured. Both systemic blood pressure and heart rate were continuously recorded. Metformin (0.01-0.3mg/kg/min) increased diameters of retinal blood vessels in a dose-dependent manner. This retinal vasodilator effect of metformin was abolished by compound C, an inhibitor of AMP-activated protein kinase (AMPK), and N(G)-nitro-L-arginine methyl ester, an inhibitor of nitric oxide (NO) synthase. Similar results were obtained with the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribonucleoside (AICAR, 0.01-1mg/kg/min). Neither metformin nor AICAR exerted significant effect on mean blood pressure and heart rate. However, a significant pressor response to AICAR was observed upon inhibition of NO synthase. These results suggest that metformin dilates retinal blood vessels through activation of AMPK, and NO plays an important role in the retinal vasodilator response following AMPK activation.
- Mefloquine inhibits voltage dependent Nav1.4 channel by overlapping the local anaesthetic binding site. [Journal Article]
- EJEur J Pharmacol 2017 Jan 03; 796:215-223
- Mefloquine constitutes a multitarget antimalaric that inhibits cation currents. However, the effect and the binding site of this compound on Na(+) channels is unknown. To address the mechanism of act...
Mefloquine constitutes a multitarget antimalaric that inhibits cation currents. However, the effect and the binding site of this compound on Na(+) channels is unknown. To address the mechanism of action of mefloquine, we employed two-electrode voltage clamp recordings on Xenopus laevis oocytes, site-directed mutagenesis of the rat Na(+) channel, and a combined in silico approach using Molecular Dynamics and docking protocols. We found that mefloquine: i) inhibited Nav1.4 currents (IC50 =60μM), ii) significantly delayed fast inactivation but did not affect recovery from inactivation, iii) markedly the shifted steady-state inactivation curve to more hyperpolarized potentials. The presence of the β1 subunit significantly reduced mefloquine potency, but the drug induced a significant frequency-independent rundown upon repetitive depolarisations. Computational and experimental results indicate that mefloquine overlaps the local anaesthetic binding site by docking at a hydrophobic cavity between domains DIII and DIV that communicates the local anaesthetic binding site with the selectivity filter. This is supported by the fact that mefloquine potency significantly decreased on mutant Nav1.4 channel F1579A and significantly increased on K1237S channels. In silico this compound docked above F1579 forming stable π-π interactions with this residue. We provide structure-activity insights into how cationic amphiphilic compounds may exert inhibitory effects by docking between the local anaesthetic binding site and the selectivity filter of a mammalian Na(+) channel. Our proposed synergistic cycle of experimental and computational studies may be useful for elucidating binding sites of other drugs, thereby saving in vitro and in silico resources.
- Blockade of patch-based μ opioid receptors in the striatum attenuates methamphetamine-induced conditioned place preference and reduces activation of the patch compartment. [Journal Article]
- EJEur J Pharmacol 2017 Jan 03; 796:207-214
- The behavioral effects of methamphetamine (METH) are mediated by the striatum, which is divided into the patch compartment, which mediates limbic and reward functions, and the matrix compartment, whi...
The behavioral effects of methamphetamine (METH) are mediated by the striatum, which is divided into the patch compartment, which mediates limbic and reward functions, and the matrix compartment, which mediates sensorimotor tasks. METH treatment results in repetitive behavior that is related to enhanced relative activation of the patch versus the matrix compartment. The patch, but not the matrix compartment contains a high density of μ opioid receptors, and localized blockade of patch-based μ opioid receptors attenuates METH-induced patch-enhanced activity and repetitive behaviors. Numerous studies have examined patch-enhanced activity and the contribution of patch-associated μ opioid receptors to METH-induced repetitive behavior, but it is not known whether patch-enhanced activity occurs during METH-mediated reward, nor is it known if patch-based μ opioid receptors contribute to METH reward. The goals of this study were to determine if blockade of patch-based μ opioid receptors alters METH-induced conditioned place preference (CPP), as well activation of the patch and matrix compartments following METH-mediated CPP. A biased conditioning paradigm was used to assess CPP, and conditioning occurred over an 8-d period. Animals were bilaterally infused in the striatum with the μ-specific antagonist CTAP or vehicle prior to conditioning. Animals were tested for preference 24h after the last day of conditioning, sacrificed and the brains processed for immunohistochemistry. Blockade of patch-based μ opioid receptors reduced METH-induced CPP, and reduced patch-enhanced c-Fos expression in the striatum following METH-mediated CPP. These data indicate that patch-enhanced activity is associated with METH-mediated reward and patch-based μ opioid receptors contribute to this phenomenon.
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- MC37, a new mono-carbonyl curcumin analog, induces G2/M cell cycle arrest and mitochondria-mediated apoptosis in human colorectal cancer cells. [Journal Article]
- EJEur J Pharmacol 2016 Dec 23; 796:139-148
- (E)-1-(3'-fluoro-[1,1'-biphenyl-3-yl)-3-(3-hydroxy-4-methoxyphenyl)prop-2-en-1-one) (MC37), a novel mono-carbonyl curcumin analog, was previously synthesized in our laboratory as a nuclear factor kap...
(E)-1-(3'-fluoro-[1,1'-biphenyl-3-yl)-3-(3-hydroxy-4-methoxyphenyl)prop-2-en-1-one) (MC37), a novel mono-carbonyl curcumin analog, was previously synthesized in our laboratory as a nuclear factor kappa B (NF-κB) inhibitor with excellent cytotoxicity against several cancer cell lines. In this study, our further investigations showed that the potent growth inhibitory activity of MC37 in human colorectal cancer cells was associated with the arrest of cell cycle progression and the induction of apoptosis. As a multi-targeted agent, MC37 inhibited the intracellular microtubule assembly, altered the expression of cyclin-dependent kinase 1 (CDK1), and ultimately induced G2/M cell cycle arrest. Moreover, MC37 collapsed the mitochondrial membrane potential (MMP), increased the Bax/Bcl-2 ratio, activated the caspase-9/3 cascade, and finally led to cancer cells apoptosis, suggesting that the mitochondrial-mediated apoptotic pathway was involved in MC37-induced apoptosis. In conclusion, these observations demonstrated that mono-carbonyl curcumin analogs would serve as multi-targeted lead for promising anti-colorectal cancer agent development.