Roles of CYP2e1 in 1,2‐dichloroethane‐induced liver damage in mice

The aim of this study was to explore the roles of cytochrome P450 2E1 (CYP2E1) in 1,2‐dichloroethane (1,2‐DCE)‐induced liver damage. Two parts were included in this study: first, effect of 1,2‐DCE on microsomal expression of CYP2E1, and second, potential of an inhibitor of CYP2E1 to reduce 1,2‐DCE‐induced liver damage. In part one, mice were exposed to 0, 0.225, 0.45, or 0.9 g/m³ 1,2‐DCE for 10 days, 3.5 h per day through static inhalation. In part two, mice were divided into blank control, solvent control, inhibitor control, 1,2‐DCE‐poisoned group, and low or high intervention group. In part one, compared to the control, serum alanine aminotransferase (ALT) activities and hepatic malondialdehyde (MDA) levels in 0.9 g/m³ 1,2‐DCE group, and microsomal CYP2E1 protein expression and activity in both 0.45 and 0.9 g/m³ 1,2‐DCE groups increased significantly; conversely, hepatic nonprotein sulfhydryl (NPSH) levels in both 0.45 and 0.9 g/m³ 1,2‐DCE groups and hepatic SOD activities in 0.9 g/m³ 1,2‐DCE group decreased significantly. In part two, microsomal CYP2E1 protein expression and activity decreased significantly in both low and high intervention groups compared to 1,2‐DCE‐poisoned group. Along with the changes of CYP2E1, hepatic MDA levels and serum ALT activities decreased; conversely, hepatic NPSH levels and SOD activities increased significantly in high intervention group. Taken together, our results suggested that 1,2‐DCE could enhance CYP2E1 protein expression and enzymatic activity, which could cause oxidative damage in liver, serving as an important mechanism underlying 1,2‐DCE‐induced liver damage. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1430–1438, 2016.     

Acute inhalation co‐exposure to 1,2‐dichloropropane and dichloromethane cause liver damage by inhibiting mitochondrial respiration and defense ability in mice

1,2‐Dichloropropane (1,2‐DCP) is used as an industrial solvent, insecticide fumigant and household dry cleaning product. Carcinogenicity caused by long‐term exposure to 1,2‐DCP is well established. However, the possible liver damage and related toxic mechanisms associated with acute inhalation exposure to 1,2‐DCP are rarely reported. In this study, we investigated the effects of individual and combined exposure to 1,2‐DCP and dichloromethane (DCM) on mice liver. The results showed that 1,2‐DCP significantly caused liver necrosis, possibly due to 1,2‐DCP‐induced inhibition of the mitochondrial respiratory chain complex I‐IV activities, resulting in mitochondrial dysfunction and extreme ATP consumption. Moreover, 1,2‐DCP also decreased mitochondrial defense ability by inhibiting the mitochondrial glutathione S‐transferase 1 (MGST1) activity, further aggravating liver damage. Additionally, we found that DCM co‐exposure potentially enhanced 1,2‐DCP toxicity. Our findings suggest that inhibition of mitochondrial function and MGST1 activity play critical roles in modulating 1,2‐DCP‐induced liver damage. Furthermore, our results contribute to study the new mechanism of mitochondria‐dominated signaling pathways underlying liver injury induced by 1,2‐DCP and DCM.     

Synthesis and Antiproliferative Activitiy of Novel Diaryl Ureas Possessing a 4H‐Pyrido[1,2‐a]pyrimidin‐4‐one Group

We herein disclose a series of novel diaryl urea derivatives possessing a 4H‐pyrido[1,2‐a]pyrimidin‐4‐one group as novel potent anticancer compounds. The structures were confirmed by IR, ¹H‐NMR, and MS. All the compounds were screened for their antiprofilerative activity agaist the human breast cancer cell line (MDA‐MB‐231). The pharmacological results indicated that most of the compounds showed moderate activity. The best of this series is compound 4c (IC₅₀ = 0.7 μmol/L), with a potency 3.6‐fold higher than Sorafenib (IC₅₀ = 2.5 μmol/L), which was approved in 2005.     

Anti‐anxiety and sedative profile evaluation of imidazo[1,2‐a]pyridine derivatives

Three imidazo[1,2‐a]pyridine‐3‐nitrosated (L‐1, L‐2, L‐3) and a 3‐formyl imidazo[1,2‐a]pyridine thiosemicarbazone (L‐4) were synthesized and evaluated for their effects in the elevated plus maze, burying behavior test, rotarod performance, the horizontal wire test, and locomotor activity. L‐2 and L‐3 increased the percent time spent in the open arms of the plus maze at doses of 1 and 2 mg/kg without modifying the number of total entries. In addition, L‐2 and L‐3 (1 mg/kg) increased the number of open arm entries indicating anxiolytic‐like activity at this dose. In the burying behavioral test, L‐1 (2–8 mg/kg), L‐2 (8 mg/kg), and L‐3 (4 and 8 mg/kg), induced a clear reduction in cumulative burying behavior, without modifying burying behavior latency, thus reducing experimental anxiety. In the rotarod test, L‐1 and L‐2 impaired rotarod performance only at the highest evaluated dose (64 mg/kg) at which reduction of motor activity was observed and thereby no conclusions about myorelaxant effects can be proposed. All compounds showed a clear sedative effect and corresponding ED₅₀ values were obtained. Results indicate that compounds L‐1, L‐2, and L‐3 show a sedative and an anxiolytic profile. Drug Dev Res 71:371–381, 2010. © 2010 Wiley‐Liss, Inc.     

Glutathione peroxidase‐1 gene rescues cocaine‐induced conditioned place preference in mice by inhibiting σ‐1 receptor expression

The aim of this study was to investigate whether the glutathione peroxidase‐1 gene (GPx‐1) affects cocaine‐induced conditioned place preference (CPP) using a mouse model. Cocaine‐induced CPP was accompanied by an increase in the level of σ‐1 receptor in the nucleus accumbens (NAc). This phenomenon was more pronounced in the GPx‐1 gene knockout (GPx‐1 KO) than in wild type (WT) mice. In contrast, the CPP and expression of σ‐1 receptor were much less pronounced in GPx‐1‐overexpressing transgenic (GPx‐1 TG) mice than non‐transgenic (non‐TG) mice. Treatment of the mice with BD1047 , a σ‐1 receptor antagonist, significantly attenuated both cocaine‐induced CPP and c‐Fos‐immunoreactivity (c‐Fos‐IR) in WT and GPx‐1 KO mice, although the effects were more evident in the latter group. Despite the protective effects of BD1047 on cocaine‐induced CPP and c‐Fos in non‐TG mice, there were no additional protective effects in cocaine‐treated GPx‐1 TG mice, indicating that the σ‐1 receptor is a critical target for GPx‐1‐mediated psychoprotective activity. Overall, our results suggest that GPx‐1 attenuates cocaine‐induced CPP via inhibition of σ‐1 receptor expression.     

N‐Malonyl‐1,2‐dihydroisoquinoline as a Novel Carrier for Specific Delivery of Drugs to the Brain

N‐Malonyl‐1,2‐dihydroisoquinoline derivatives were synthesized and investigated as a novel carrier system for site‐specific and sustained delivery of drugs to the brain. Such carriers are expected to be stable against air oxidation due to the presence of the carbonyl group close to nitrogen of the dihydroisoquinoline. Reduction of the prepared isoquinolinium quaternary derivatives with sodium dithionite afforded a novel group of N‐malonyl‐1,2‐dihydroisoquinoline chemical delivery systems (CDS). The synthesized N‐malonyl‐1,2‐dihydroisoquinoline chemical delivery systems were subjected to various chemical and biological investigations to evaluate their ability to cross the blood‐brain barrier (BBB), and to be oxidized biologically into their corresponding quaternary derivatives. The in‐vitro oxidation studies showed that the designed N‐malonyl‐1,2‐dihydroisoquinoline chemical delivery system could be oxidized into its corresponding quaternary derivatives at an adequate rate. The in‐vivo distribution studies showed that these N‐malonyl‐1,2‐dihydroisoquinoline chemical delivery systems were able to cross the blood‐brain barrier at detectable concentrations.     

Increased expression of miR‐34a in mouse spleen one day after exposure to N‐ethyl‐N‐nitrosourea

MicroRNAs (miRNAs) are a class of single‐stranded small RNA molecules (~22 nucleotides) that are not translated into proteins and function as regulators of gene expression. Many miRNAs are involved in carcinogenesis. One of them, miR‐34a, is associated with various p53‐initiated biological processes and may act as a tumor suppressor miRNA. Its expression is generally down‐regulated in tumor tissues and up‐regulated in tissues exposed to carcinogens chronically or subchronically. However, the response of this miRNA to acute exposure of a genotoxic carcinogen is little known. In this study, miR‐34a expression was evaluated in spleen tissues of mice treated with a dose of 120 mg kg^?1 body weight N‐ethyl‐N‐nitrosourea (ENU), a potent mutagenic carcinogen. Real‐time PCR analysis showed that the ENU exposure resulted in a 5.5‐fold increase of miR‐34a expression over the control one day after the treatment. The result suggests that miR‐34a expression responds sensitively to genotoxic insults within a short period after exposure of the mutagen, and therefore, this gene has the potential to be used as an indicator for genotoxin exposure.     

Design,Synthesis and Biological Evaluation of Imidazo[1,2‐a]pyridine Derivatives as Novel DPP‐4 Inhibitors

A new series of DPP‐4 inhibitors with imidazo[1,2‐a]pyridine scaffold were designed by exploiting scaffold hopping strategy and docking study. Based on docking binding model, structural modifications of 2‐benzene ring and pyridine moieties of compound 5a led to the identification of compound 5d with 2, 4‐dichlorophenyl group at the 2‐position as a potent (IC₅₀ = 0.13 μm ), selective (DPP‐8/DPP‐4 = 215 and DPP‐9/DPP‐4 = 192) and in vivo efficacious DPP‐4 inhibitor. Further, molecular docking revealed that compound 5d could retain key binding features of DPP‐4 with the pyridine moiety of imidazo[1,2‐a]pyridine ring providing an additional π?π interaction with Phe357 of DPP‐4. Compound 5d might be a promising lead for further development of novel DPP‐4 inhibitor treating T2DM.     

New insights into the mechanism of action of pyrazolo[1,2‐a]benzo[1,2,3,4]tetrazin‐3‐one derivatives endowed with anticancer potential

Due to the scarce biological profile, the pyrazolo[1,2‐a]benzo[1,2,3,4]tetrazine‐3‐one scaffold (PBT) has been recently explored as promising core for potential anticancer candidates. Several suitably decorated derivatives (PBTs) exhibited antiproliferative activity in the low‐micromolar range associated with apoptosis induction and cell cycle arrest on S phase. Herein, we selected the most active derivatives and submitted them to further biological explorations to deepen the mechanism of action. At first, a DNA targeting is approached by means of flow Linear Dichroism experiments so as to evaluate how small planar molecules might interact with DNA, including the interference with the catalytic cycle of topoisomerase II and the influence on the cleavable complex stabilization (poisoning effect). In support of the experimental data, in silico studies have been achieved to better understand the chemical space of the interactions. Interestingly some meaningful structural features, useful for further developments, were found. The 8,9‐di‐Cl substituted derivative revealed as the most effective in the intercalative process, as well as on the inhibition of catalytic activity of topoisomerase II. Predicted ADME studies confirm that PBTs are promising as potential drug candidates.     

Overexpression of miR‐138‐5p suppresses MnCl2‐induced autophagy by targeting SIRT1 in SH‐SY5Y cells

The mechanism of manganism caused by manganese (Mn), an important environmental risk factor for Parkinson's disease, is still unclear. Recent evidence suggested that autophagy participated in neurodegenerative diseases, in which microRNA played a crucial role. However, roles of microRNA in the aberrant autophagy that occurs in neurodegenerative diseases remains controversial. In nervous system, miRNA‐138‐5p is highly expressed and plays a key role in regulating memory and axon regeneration. Importantly, we also found that miR‐138‐5p expression decreased significantly after SH‐SY5Y cells exposed to manganese chloride (MnCl₂) in previous study. To explore the role of miR‐138‐5p in Mn‐induced autophagy, autophagy associated indicators were detected. And we found that MnCl₂ could induce autophagic dysregulation and inhibit expression of miR‐138‐5p. While the levels of LC3‐II/LC3‐I, Beclin1, and p62, the number of autophagosome formation significantly decreased after miR‐138‐5p over‐expression, which demonstrated that miR‐138‐5p could clearly retard Mn‐induced autophagy. In additional, we found there were classical and evolutionarily conserved miR‐138‐5p binding sites in 3′‐UTR region of SIRT1, which was inhibited when overexpression of miR‐138‐5p. Therefore, it was speculated that elevated expression of SIRT1 may be resulted from inhibition of miR‐138‐5p after cells exposed to MnCl₂. Finally, we found that SIRT1 inhibitor EX‐527 suppressed Mn‐induced autophagy as well as miR‐138‐5p, while the suppression was reversed by SIRT1‐specific activator SRT1720. These results indicated that overexpression of miR‐138‐5p suppressed Mn‐induced autophagy by targeting SIRT1.     

Dexmedetomidine‐induced contraction involves c‐Jun NH2‐terminal kinase phosphorylation through activation of the 5‐lipoxygenase pathway in the isolated endothelium‐denuded rat aorta

Vasoconstriction induced by dexmedetomidine, a highly selective alpha‐2 adrenoceptor agonist, mainly involves c‐Jun NH₂‐terminal kinase (JNK) phosphorylation in the isolated endothelium‐denuded aorta. We carried out an in vitro study to determine the main arachidonic acid metabolic pathway that is involved in dexmedetomidine‐induced JNK activation. Cumulative dexmedetomidine concentration‐contractile response curves were generated in the endothelium‐denuded rat aorta in the presence or absence of the following inhibitors: the JNK inhibitor SP600125, the phospholipase A₂ inhibitor quinacrine dihydrochloride, the non‐specific lipoxygenase (LOX) inhibitor nordihydroguaiaretic acid, the 5‐LOX inhibitor AA‐861, the dual 5‐LOX and cyclooxygenase (COX) inhibitor phenidone, the non‐specific COX inhibitor indomethacin, the cytochrome p450 epoxygenase inhibitor fluconazole, the COX‐1 inhibitor SC‐560, and the COX‐2 inhibitor NS‐398. The effect of the alpha‐2 adrenoceptor inhibitor rauwolscine and other inhibitors, such as quinacrine dihydrochloride, nordihydroguaiaretic acid, AA‐861, phenidone, indomethacin and the protein kinase C inhibitor GF 109203X, on dexmedetomidine‐induced JNK phosphorylation was investigated in rat aortic vascular smooth muscle cells with western blotting. The effect of dexmedetomidine on 5‐LOX and COX‐2 expression was investigated in vascular smooth muscle cells. SP600125, quinacrine dihydrochloride, nordihydroguaiaretic acid, AA‐861, phenidone, rauwolscine and chelerythrine attenuated dexmedetomidine‐induced contraction. Indomethacin slightly attenuated dexmedetomidine‐induced contraction. Fluconazole and SC‐560 had no effect on dexmedetomidine‐induced contraction, whereas NS‐398 attenuated contraction. SP600125, rauwolscine, quinacrine dihydrochloride, nordihydroguaiaretic acid, AA‐861, phenidone and GF 109203X attenuated dexmedetomidine‐induced JNK phosphorylation. 5‐LOX and COX‐2 were upregulated by dexmedetomidine. Thus, dexmedetomidine‐induced alpha‐2 adrenoceptor‐mediated contraction is mediated mainly by 5‐LOX and partially by COX‐2, which leads to JNK phosphorylation.     

Long noncoding RNA H19 acts as a miR‐340‐3p sponge to promote epithelial‐mesenchymal transition by regulating YWHAZ expression in paclitaxel‐resistant breast cancer cells

Breast cancer (BC) is the leading cause of cancer‐related death in women worldwide and one of the most prevalent malignancy. In recent years, increasing evidence had illuminated that long noncoding RNAs (lncRNAs) serve as critical factors in multiple tumor progression, including BC. Emerging references had indicated that the lncRNA H19 acts as significant roles in tumor progression and epithelial‐mesenchymal transition (EMT). However, the underlying molecular mechanisms and biological roles of H19 in BC invasion, metastasis and EMT are still unclear. In this study, it was detected that the expression level of H19 was increased in BC paclitaxel‐resistant (PR) cells subline (MCF‐7/PR) in comparison with MCF‐7 parental cells. In vitro, there were demonstrated that H19 overexpression promoted BC cells proliferation, metastasis, invasion and EMT procedures, and suppressed cells apoptosis. Whereas, H19 suppression resulted in the contrary biological effects. Besides, bioinformatics tools and dual‐luciferase reporters assays indicated that miR‐340‐3p could act as a potential target gene of H19, the underlying mechanism studies proved that H19 could act as a competing endogenous RNA (ceRNA) via competitively binding miR‐340‐3p to promote BC cell proliferation, metastasis and EMT by regulating tyrosine 3‐monooxygenase/tryptophan 5‐monooxygenase activation protein zeta (YWHAZ) and potentiate the Wnt/β‐catenin signaling in BC cells. In summary, our findings demonstrated that H19 could act as a ceRNA in BC progression, metastasis and EMT through modulating miR‐340‐3p/YWHAZ axis and activating the canonical Wnt/β‐catenin signaling pathway, indicating that H19 might act as an underlying therapeutic target and prognostic biomarker for BC therapy.     

Exacerbated cardiac fibrosis induced by β‐adrenergic activation in old mice due to decreased AMPK activity

Senescent hearts exhibit defective responses to β‐adrenergic receptor (β‐AR) over‐activation upon stress, leading to more severe pathological cardiac remodelling. However, the underlying mechanisms remain unclear. Here, we investigated the role of adenosine monophosphate‐activated protein kinase (AMPK) in protecting against ageing‐associated cardiac remodelling in mice upon β‐AR over‐activation. 10‐week‐old (young) and 18‐month‐old (old) mice were subcutaneously injected with the β‐AR agonist isoproterenol (ISO; 5 mg/kg). More extensive cardiac fibrosis was found in old mice upon ISO exposure than in young mice. Meanwhile, ISO treatment decreased AMPK activity and increased β‐arrestin 1, but not β‐arrestin 2, expression, and the effects of ISO on AMPK and β‐arrestin 1 were greater in old mice than in young mice. Similarly, young AMPKα2‐knockout (KO) mice showed more extensive cardiac fibrosis upon ISO exposure than that was observed in age‐matched wild‐type (WT) littermates. The extent of cardiac fibrosis in WT old mice was similar to that in young KO mice. Additionally, AMPK activities were decreased and β‐arrestin 1 expression increased in KO mice. In contrast, the AMPK activator metformin decreased β‐arrestin 1 expression and attenuated cardiac fibrosis in both young and old mice upon ISO exposure. In conclusion, more severe cardiac fibrosis is induced by ISO in old mice than in young mice. A decrease in AMPK activity, which further increases β‐arrestin 1 expression, is the central mechanism underlying the ageing‐related cardiac fibrosis induced by ISO. The AMPK activator metformin is a promising therapeutic agent for treating ageing‐related cardiac remodelling upon β‐AR over‐activation.     

Hepatoprotective effects of salidroside on fulminant hepatic failure induced by d‐galactosamine and lipopolysaccharide in mice

Objectives The aim was to investigate the protective effect of salidroside isolated from Rhodiola sachalinensis A. Bor. (Crassulaceae) on d ‐galactosamine/lipopolysaccharide‐induced fulminant hepatic failure. Methods Hepatotoxicity was induced by an intraperitoneal injection of d ‐galactosamine (700 mg/kg) and lipopolysaccharide (10 μg/kg); salidroside (20, 50 and 100 mg/kg) was administered intraperitoneally 1 h before induction of hepatoxicity. Liver injury was assessed biochemically and histologically. Key findings Salidroside attenuated the induced acute increase in serum aspartate aminotransferase and alanine aminotransferase activities, and levels of tumour necrosis factor‐alpha levels and serum nitric oxide. It restored depleted hepatic glutathione, superoxide dismutase, catalase and glutathione peroxidase activities, decreased malondialdehyde levels and considerably reduced histopathological changes. Histopathological, immunohistochemical and Western blot analyses also demonstrated that salidroside could reduce the appearance of necrotic regions and expression of caspase‐3 and hypoxia‐inducible factor‐1α in liver tissue. Conclusions Salidroside protected liver tissue from the oxidative stress elicited by d ‐galactosamine and lipopolysaccharide. The hepatoprotective mechanism of salidroside appear to be related to antioxidant activity and inhibition of hypoxia‐inducible factor‐1α.