Qian Bu

NMR-based metabonomic study of the sub-acute toxicity of titanium dioxide nanoparticles in rats after oral administration

As titanium dioxide nanoparticles (TiO(2) NPs) are widely used commercially, their potential toxicity on human health has attracted particular attention. In the present study, the oral toxicological effects of TiO(2) NPs (dosed at 0.16, 0.4 and 1 g kg( - 1), respectively) were investigated using conventional approaches and metabonomic analysis in Wistar rats. Serum chemistry, hematology and histopathology examinations were performed. The urine and serum were investigated by (1)H nuclear magnetic resonance (NMR) using principal components and partial least squares discriminant analysis. The metabolic signature of urinalysis in TiO(2) NP-treated rats showed increases in the levels of taurine, citrate, hippurate, histidine, trimethylamine-N-oxide (TMAO), citrulline, alpha-ketoglutarate, phenylacetylglycine (PAG) and acetate; moreover, decreases in the levels of lactate, betaine, methionine, threonine, pyruvate, 3-D-hydroxybutyrate (3-D-HB), choline and leucine were observed. The metabonomics analysis of serum showed increases in TMAO, choline, creatine, phosphocholine and 3-D-HB as well as decreases in glutamine, pyruvate, glutamate, acetoacetate, glutathione and methionine after TiO(2) NP treatment. Aspartate aminotransferase (AST), creatine kinase (CK) and lactate dehydrogenase (LDH) were elevated and mitochondrial swelling in heart tissue was observed in TiO(2) NP-treated rats. These findings indicate that disturbances in energy and amino acid metabolism and the gut microflora environment may be attributable to the slight injury to the liver and heart caused by TiO(2) NPs. Moreover, the NMR-based metabolomic approach is a reliable and sensitive method to study the biochemical effects of nanomaterials.

Taurine attenuates methamphetamine-induced autophagy and apoptosis in PC12 cells through mTOR signaling pathway

Methamphetamine (METH), a commonly abused psychostimulant, has been shown to induce neuronal damage by causing reactive oxygen species (ROS) formation, apoptosis and autophagy. Taurine (2-aminoethanesulfonic acid) is involved in several physiological actions in the brain, including neuroprotection, osmoregulation and neurotransmission. In this study, we investigate the protective effect of taurine against METH-induced neurotoxicity in PC12 cells and the underlying mechanism. The results showed that taurine significantly increased the cell viability inhibited by METH. LC3-II expression was elevated by METH treatment, whereas such increase was obviously attenuated by taurine. Co-treatment of taurine strongly reversed the decline of antioxidase activities induced by METH. Moreover, phosphorylated mammalian target of rapamycin (p-mTOR) was significantly inhibited by METH, whereas complementation of taurine markedly increased the expression of p-mTOR in PC12 cells, rather than phosphorylated Erk. Interestingly, taurine-induced decreasing expression of LC3-II was partially blocked by pretreatment of RAD001, an mTOR inhibitor. These results indicated that taurine inhibits METH-induced autophagic process through activating mTOR rather than Erk signaling. Collectively, our study shows that taurine protects METH-induced PC12 cells damage by attenuating ROS production, apoptosis and autophagy, at least in part, via mTOR signaling pathway.

1H-NMR based metabonomic profiling of human esophageal cancer tissue

BackgroundThe biomarker identification of human esophageal cancer is critical for its early diagnosis and therapeutic approaches that will significantly improve patient survival. Specially, those that involves in progression of disease would be helpful to mechanism research.MethodsIn the present study, we investigated the distinguishing metabolites in human esophageal cancer tissues (n = 89) and normal esophageal mucosae (n = 26) using a 1H nuclear magnetic resonance (1H-NMR) based assay, which is a highly sensitive and non-destructive method for biomarker identification in biological systems. Principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA) and orthogonal partial least-squares-discriminant anlaysis (OPLS-DA) were applied to analyse 1H-NMR profiling data to identify potential biomarkers.ResultsThe constructed OPLS-DA model achieved an excellent separation of the esophageal cancer tissues and normal mucosae. Excellent separation was obtained between the different stages of esophageal cancer tissues (stage II = 28; stage III = 45 and stage IV = 16) and normal mucosae. A total of 45 metabolites were identified, and 12 of them were closely correlated with the stage of esophageal cancer. The downregulation of glucose, AMP and NAD, upregulation of formate indicated the large energy requirement due to accelerated cell proliferation in esophageal cancer. The increases in acetate, short-chain fatty acid and GABA in esophageal cancer tissue revealed the activation of fatty acids metabolism, which could satisfy the need for cellular membrane formation. Other modified metabolites were involved in choline metabolic pathway, including creatinine, creatine, DMG, DMA and TMA. These 12 metabolites, which are involved in energy, fatty acids and choline metabolism, may be associated with the progression of human esophageal cancer.ConclusionOur findings firstly identify the distinguishing metabolites in different stages of esophageal cancer tissues, indicating the attribution of metabolites disturbance to the progression of esophageal cancer. The potential biomarkers provide a promising molecular diagnostic approach for clinical diagnosis of human esophageal cancer and a new direction for the mechanism study.

Zinc oxide nanoparticles cause nephrotoxicity and kidney metabolism alterations in rats

Although zinc oxide nanoparticles (ZnO NPs) have been widely used, their potential hazards on mammalian and human remain largely unknown. In this study, the biochemical compositions of urine and kidney from the rats treated with ZnO NPs (100, 300 and 1000 mg/kg, respectively) were investigated using 1H nuclear magnetic resonance (NMR) technique with the pattern recognition of partial least squares-discriminant analysis. Hematology, clinical biochemistry and kidney histopathological examinations were also performed. Metabolic profiles from rats treated with ZnO NPS exhibited increases in the levels of taurine, lactate, acetate, creatine, phosphocholine, trimethylamine-N-oxide, α-glucose, and 3-D-hydroxybutyrate, as well as decreases in lipid, succinate, citrate, α-ketoglutarate, hippurate and 4-hydroxyphenylacetic acid in urine after ZnO NPs treatment for 14 days. A similar alteration pattern was also identified in kidney. Urine choline and phosphocholine increased significantly shortly after ZnO NPs treatment, moreover, some amino acids and glucose also increased during the experimental period. However, succinate, citrate and α-ketoglutarate in urine exhibited a different alteration trend, which showed increases on the first day after ZnO NPs treatment, but decreases gradually until the termination of the study. A similar alteration pattern of urinary 1H NMR spectra was also detected in kidney. Moreover, ZnO NPs (1000 mg/kg) resulted in significant increases in serum creatine and blood urea nitrogen, decreases in hemoglobin, haematocrit and mean corpuscular hemoglobin concentration, and overt tubular epithelial cell necrosis. These findings show that ZnO NPs can disturb the energy metabolism and cause mitochondria and cell membrane impairment in rat kidney, which may contribute to ZnO NPs-induced nephrotoxicity.

Transcriptome analysis of long non-coding RNAs of the nucleus accumbens in cocaine-conditioned mice

Cocaine dependence involves in the brains reward circuit as well as nucleus accumbens (NAc), a key region of the mesolimbic dopamine pathway. Many studies have documented altered expression of genes and identified transcription factor networks and epigenetic processes that are fundamental to cocaine addiction. However, all these investigations have focused on mRNA of encoding genes, which may not always reflect the involvement of long non‐coding RNAs (lncRNAs), which has been implied in a broad range of biological processes and complex diseases including brain development and neuropathological process. To explore the potential involvement of lncRNAs in drug addiction, which is viewed as a form of aberrant neuroplasticity, we used a custom‐designed microarray to examine the expression profiles of mRNAs and lncRNAs in brain NAc of cocaine‐conditioned mice and identified 764 mRNAs, and 603 lncRNAs were differentially expressed. Candidate lncRNAs were identified for further genomic context characterization as sense‐overlap, antisense‐overlap, intergenic, bidirection, and ultra‐conserved region encoding lncRNAs. We found that 410 candidate lncRNAs which have been reported to act in cis or trans to their targeted loci, providing 48 pair mRNA‐lncRNAs. These results suggest that the modification of mRNAs expression by cocaine may be associated with the actions of lncRNAs. Taken together, our results show that cocaine can cause the genome‐wide alterations of lncRNAs expressed in NAc, and some of these modified RNA transcripts may to play a role in cocaine‐induced neural plasticity and addiction.

Proteomic analysis of the nucleus accumbens in rhesus monkeys of morphine dependence and withdrawal intervention

It has been known that the reinforcing effects and long-term consequences of morphine are closely associated with nucleus accumbens (NAc) in the brain, a key region of the mesolimbic dopamine pathway. However, the proteins involved in neuroadaptive processes and withdrawal symptom in primates of morphine dependence have not been well explored. In the present study, we performed proteomes in the NAc of rhesus monkeys of morphine dependence and withdrawal intervention with clonidine or methadone. Two-dimensional electrophoresis was used to compare changes in cytosolic protein abundance in the NAc. We found a total of 46 proteins differentially expressed, which were further identified by mass spectrometry analysis. The identified proteins can be classified into 6 classes: metabolism and mitochondrial function, synaptic transmission, cytoskeletal proteins, oxidative stress, signal transduction and protein synthesis and degradation. Importantly, we discovered 14 proteins were significantly but similarly altered after withdrawal therapy with clonidine or methadone, revealing potential pharmacological strategies or targets for the treatment of morphine addiction. Our study provides a comprehensive understanding of the neuropathophysiology associated with morphine addiction and withdrawal therapy in primate, which is helpful for the development of opiate withdrawal pharmacotherapies.

Metabolomics: A Revolution for Novel Cancer Marker Identification

The repertoire of small-molecular-weight substances present in cells, tissue and body fluids are known as the metabolites. The global analysis of metabolites, such as by high-resolution ¹H nuclear magnetic resonance spectroscopy and mass spectrometry, is integral to the rapidly expanding field of metabolomics, which is making progress in various diseases. In the area of cancer and metabolic phenotype, the integrated analysis of metabolites may provide a powerful platform for detecting changes related to cancer diagnosis and discovering novel biomarkers. In this review, metabolomics including the technologies in metabolomics research and extracting information from metabolomics datasets are described. Then we discuss the challenges and opportunities in metabolomics for finding metabolic processes in cancer and discovering novel cancer biomarkers. Finally, we assess the clinical applicability of metabolomics.

NMR-based metabonomic in hippocampus, nucleus accumbens and prefrontal cortex of methamphetamine-sensitized rats

(1)H NMR spectroscopy was applied to investigate the changes of cerebral metabolites in brain hippocampus, nucleus accumbens (NAC) and prefrontal cortex (PFC) of the rats subjected to subcutaneous twice-daily injections of 2.5mg/kg methamphetamine (MAP) for 7 days. The results indicated that MAP exposure induced significant behavioral sensitization and altered cerebral metabolites in rats. The neurotransmitters glutamate, glutamine and GABA significantly decreased in hippocampus, NAC and PFC. Specifically, increased succinic acid semialdehyde, a metabolism product of GABA, was observed in hippocampus. Additionally, decreased serotonin was observed in both NAC and PFC, whereas decreased dopamine was only observed in NAC after repeated MAP treatment. Glutathione obviously decreased in above brain regions, whereas acetylcysteine declined in hippocampus and NAC, and taurine declined in NAC and PFC. Homocysteic acid was elevated in hippocampus and NAC by repeated MAP administration. Membrane ingredients like phosphocholine elevated in response to MAP administration in NAC and PFC. N-Acetyl-aspartate, a marker of neuronal viability, decreased in the three regions; however, myo-inositol, a glial cell marker, increased in hippocampus and PFC. Tricarboxylic acid cycle intermediate products, such as α-ketoglutarate, succinate, citrate and the methionine significantly decreased in above three brain regions after MAP administration; however, ADP decreased in hippocampus. These results indicate that repeated MAP treatment causes neurotransmitters disturbance, imbalance between oxidative stress and antioxidants, and gliosis in hippocampus, NAC and PFC. Profound metabolic changes detected across brain regions provide the first evidence of metabonomic changes in MAP-induced sensitized rats.

1H NMR-based metabonomic analysis of brain in rats of morphine dependence and withdrawal intervention

Metabolic consequences of morphine dependence and withdrawal intervention have not been well explored. In the present study, the metabolic changes in brain hippocampus, nucleus accumbens (NAc), prefrontal cortex (PFC) and striatum of rats with morphine dependence and withdrawal intervention were explored by using ¹H nuclear magnetic resonance coupled with principal component analysis, partial least squares and orthogonal signal correction analysis. We found that the concentrations of neurotransmitters including glutamate, glutamine and gamma-aminobutyric acid changed differentially in hippocampus, NAc, PFC and striatum after repeated morphine treatment. Significant changes were also found in a number of cerebral metabolites including N-acetyl aspartate (NAA), lactic acid, creatine, myo-inositol and taurine. These findings indicate the profound disturbances of energy metabolism, amino acid metabolism and neurotransmitters caused by chronic morphine treatment. Interestingly, morphine-induced changes in lactic acid, creatine and NAA were clearly reversed by intervention of methadone or clonidine. Our study provides a comprehensive understanding of the metabolic alteration associated with morphine addiction and withdrawal therapy, which may help to develop new pharmacotherapies.

Small molecular anticancer agent SKLB703 induces apoptosis in human hepatocellular carcinoma cells via the mitochondrial apoptotic pathway in vitro and inhibits tumor growth in vivo

Inducing apoptosis is a promising therapeutic approach to overcome cancer. Here we described that a novel synthesized compound, 3-amino-N-(4-chlorobenzyl)-6-(3-methoxyphenyl)thieno[2,3-b]pyridine-2-carboxamide (SKLB703), exhibits antitumor activity via inducing apoptosis both invitro and invivo. Our results showed that SKLB703 inhibited the proliferation of a panel of human cancer cell lines, and human hepatocellular carcinoma cell line HepG2 was the most sensitive. The proliferation inhibitory effect of SKLB703 was associated with its apoptosis-inducing effect by activating caspase-3 and caspase-9 rather than caspase 8. Exposure of HepG2 to SKLB703 also resulted in Bax upregulation, Bcl-2 downregulation, cytochrome c release and mitochondrial transmembrane potential change in mitochondrial apoptotic pathway. Moreover, the decrease of phosphorylated p 44/42 mitogen-activated protein kinase and phosphorylated Akt was observed. SKLB703 suppressed the growth of established tumors in xenograft models in mice, whereas no toxicity was exhibited. TUNAL analysis showed that SKLB703 induced HepG2 tumor apoptosis. Taken together, the present study demonstrates that SKLB730 exhibits its antitumor activity through inducing apoptosis via mitochondrial apoptotic pathway. Its potential to be a candidate of anticancer agent is worth being further investigated.