Minjiang Chen

Systemic and characteristic metabolites in the serum of streptozotocin-induced diabetic rats at different stages as revealed by a 1H-NMR based metabonomic approach

Diabetes mellitus is a typical heterogeneous metabolic disorder characterized by abnormal metabolism of carbohydrates, lipids, and proteins. Investigating the changes in metabolic pathways during the evolution of diabetes mellitus may contribute to the understanding of its metabolic features and pathogenesis. In this study, serum samples were collected from diabetic rats and age-matched controls at different time points: 1 and 9 weeks after streptozotocin (STZ) treatment. (1)H nuclear magnetic resonance ((1)H NMR)-based metabonomics with quantitative analysis was performed to study the metabolic changes. The serum samples were also subjected to clinical chemistry analysis to verify the metabolic changes observed by metabonomics. Partial least squares discriminant analysis (PLS-DA) demonstrated that the levels of serum metabolites in diabetic rats are different from those in control rats. These findings indicate that the metabolic characteristics of the two groups are markedly different at 1 and 9 weeks. Quantitative analysis showed that the levels of some metabolites, such as pyruvate, lactate, citrate, acetone, acetoacetate, acetate, glycerol, and valine, varied in a time-dependent manner in diabetic rats. These results suggest that serum metabolites related to glycolysis, the tricarboxylic acid cycle, gluconeogenesis, fatty acid β-oxidation, branched-chain amino acid metabolism, and the tyrosine metabolic pathways are involved in the evolution of diabetes. The metabolic changes represent potential features and promote a better understanding of the mechanisms involved in the development of diabetes mellitus. This work further suggests that (1)H NMR metabonomics is a valuable approach for providing novel insights into the pathogenesis of diabetes mellitus and its complications.

Analysis of neuron-astrocyte metabolic cooperation in the brain of db/db mice with cognitive decline using 13C NMR spectroscopy.

Type 2 diabetes has been linked to cognitive impairment, but its potential metabolic mechanism is still unclear. The present study aimed to explore neuron–astrocyte metabolic cooperation in the brain of diabetic (db/db, BKS.Cg-m+/+ Leprdb/J) mice with cognitive decline using 13C NMR technique in combination with intravenous [2-13C]-acetate and [3-13C]-lactate infusions. We found that the 13C-enrichment from [2-13C]-acetate into tricarboxylic acid cycle intermediate, succinate, was significantly decreased in db/db mice with cognitive decline compared with wild-type (WT, C57BLKS/J) mice, while an opposite result was obtained after [3-13C]-lactate infusion. Relative to WT mice, db/db mice with cognitive decline had significantly lower 13C labeling percentages in neurotransmitters including glutamine, glutamate, and γ-aminobutyric acid after [2-13C]-acetate infusion. However, [3-13C]-lactate resulted in increased 13C-enrichments in neurotransmitters in db/db mice with cognitive decline. This may indicate that the disturbance of neurotransmitter metabolism occurred during the development of cognitive decline. In addition, a reduction in 13C-labeling of lactate and an increase in gluconeogenesis were found from both labeled infusions in db/db mice with cognitive decline. Therefore, our results suggest that the development of cognitive decline in type 2 diabetes may be implicated to an unbalanced metabolism in neuron–astrocyte cooperation and an enhancement of gluconeogenesis.

Cognitive decline in type 2 diabetic db/db mice may be associated with brain region-specific metabolic disorders

Type 2 diabetes has been associated with cognitive decline, but its metabolic mechanism remains unclear. In the present study, we attempted to investigate brain region-specific metabolic changes in db/db mice with cognitive decline and explore the potential metabolic mechanism linking type 2 diabetes and cognitive decline. We analyzed the metabolic changes in seven brain regions of two types of mice (wild-type mice and db/db mice with cognitive decline) using a 1H NMR-based metabolomic approach. Then, a mixed-model analysis was used to evaluate the effects of mice type, brain region, and their interaction on metabolic changes. Compared with the wild-type mice, the db/db mice with cognitive decline had significant increases in lactate, glutamine (Gln) and taurine as well as significant decreases in alanine, aspartate, choline, succinate, γ-Aminobutyric acid (GABA), glutamate (Glu), glycine, N-acetylaspartate, inosine monophosphate, adenosine monophosphate, adenosine diphosphate, and nicotinamide adenine dinucleotide. Brain region-specific metabolic differences were also observed between these two mouse types. In addition, we found significant interaction effects of mice type and brain region on creatine/phosphocreatine, lactate, aspartate, GABA, N-acetylaspartate and taurine. Based on metabolic pathway analysis, the present study suggests that cognitive decline in db/db mice might be linked to a series of brain region-specific metabolic changes, involving an increase in anaerobic glycolysis, a decrease in tricarboxylic acid (TCA) and Gln-Glu/GABA cycles as well as a disturbance in lactate-alanine shuttle and membrane metabolism.

Prediction and diagnosis of renal cell carcinoma using nuclear magnetic resonance-based serum metabolomics and self-organizing maps

Diagnosis of renal cell carcinoma (RCC) at an early stage is challenging, but it provides the best chance for cure. We aimed to develop a predictive diagnostic method for early-stage RCC based on a biomarker cluster using nuclear magnetic resonance (NMR)-based serum metabolomics and self-organizing maps (SOMs). We trained and validated the SOM model using serum metabolome data from 104 participants, including healthy individuals and early-stage RCC patients. To assess the predictive capability of the model, we analyzed an independent cohort of 22 subjects. We then used our method to evaluate changes in the metabolic patterns of 23 RCC patients before and after nephrectomy. A biomarker cluster of 7 metabolites (alanine, creatine, choline, isoleucine, lactate, leucine, and valine) was identified for the early diagnosis of RCC. The trained SOM model using a biomarker cluster was able to classify 22 test subjects into the appropriate categories. Following nephrectomy, all RCC patients were classified as healthy, which was indicative of metabolic recovery. But using a diagnostic criterion of 0.80, only 3 of the 23 subjects could not be confidently assessed as metabolically recovered after nephrectomy. We successfully followed-up 17 RCC patients for 8 years post-nephrectomy. Eleven of these patients who diagnosed as metabolic recovery remained healthy after 8 years. Our data suggest that a SOM model using a biomarker cluster from serum metabolome can accurately predict early RCC diagnosis and can be used to evaluate postoperative metabolic recovery.

Interactions between interleukin-6 and myeloid-derived suppressor cells drive the chemoresistant phenotype of hepatocellular cancer

Abstract Emerging evidence implicates an important role for myeloid‐derived suppressor cells (MDSCs) in tumor growth, angiogenesis and metastasis. However, limited knowledge is known about the function of MDSCs in response to chemotherapies. In this study, we find that drug‐resistant hepatocellular cancer (HCC) cells‐derived conditioned medium significantly enhances the expansion and immunosuppressive function of MDSCs compared to their parental sensitive cells, which is demonstrated by increased level of arginase, nitric oxide (NO), and reactive oxygen species (ROS). Next, we reveal that drug‐resistant HCC cells‐derived IL‐6 activated MDSCs, which is demonstrated by using an anti‐IL‐6 neutralizing antibody that caused a reduced MDSC immunosuppressive activity. More importantly, the depletion of MDSC via the administration of anti‐Gr‐1 antibody or the blockade of IL‐6 signaling sensitized 5‐FU‐resistant H22 hepatoma to chemotherapy in the immunocompetent C57BL/6N mice. In primary human HCC, IL‐6 expression levels strongly correlate with an MDSC phenotype and chemotherapy response in HCC patients. In conclusion, these results describe a role of IL‐6 in the drug resistance in HCC chemotherapy and suggest that MDSC‐targeting treatments may be potential therapeutic strategy for HCC chemoresistance. Graphical abstract Figure. No Caption available. HighlightsDrug‐resistant HCC cells‐derived IL‐6 enhances the expansion and activity of MDSCs;MDSC depletion or IL‐6 blockade enhances the therapeutic efficacy of chemotherapy;IL‐6 expression correlates with the markers of MDSCs and chemotherapy response.

Identification of key metabolic changes in renal interstitial fibrosis rats using metabonomics and pharmacology

Renal fibrosis is one of the important pathways involved in end-stage renal failure. Investigating the metabolic changes in the progression of disease may enhance the understanding of its pathogenesis and therapeutic information. In this study, 1H-nuclear magnetic resonance (NMR)-based metabonomics was firstly used to screen the metabolic changes in urine and kidney tissues of renal interstitial fibrotic rats induced by unilateral ureteral obstruction (UUO), at 7, 14, 21, and 28 days after operation, respectively. The results revealed that reduced levels of bioenergy synthesis and branched chain amino acids (BCAAs), as well as elevated levels of indoxyl sulfate (IS) are involved in metabolic alterations of renal fibrosis rats. Next, by pharmacological treatment we found that reduction of IS levels could prevent the renal fibrotic symptoms. Therefore, we suggested that urinary IS may be used as a potential biomarker for the diagnosis of renal fibrosis, and a therapeutic target for drugs. Novel attempt combining metabonomics and pharmacology was established that have ability to provide more systematic diagnostic and therapeutic information of diseases.

Shikonin potentiates the effect of arsenic trioxide against human hepatocellular carcinoma in vitro and in vivo.

Hepatocellular carcinoma (HCC) is a highly lethal malignancy mostly because of metastasis, recurrence and acquired resistance to conventional chemotherapy. Arsenic trioxide (ATO) is successfully used to treat hematological malignancies, and has been proven to trigger apoptosis in HCC cells. However, the phase II trial evaluating the efficacy and toxicity of ATO in patients with HCC showed that single-agent ATO is poorly active against HCC. Therefore, it is of great importance to develop effective chemosensitization agents to ATO. The aim of the present study was to determine whether shikonin (SHI), a natural product from the root of lithospermum erythrorhizon, could synergistically enhance the anti-HCC efficacy of ATO both in vitro and in vivo. We found that the combination of SHI and ATO exhibited synergistic anticancer efficacy and achieved greater selectivity between cancer cells and normal cells. By inducing intracellular oxidative stress, SHI potentiated ATO-induced DNA damage, followed by increased activation of endoplasmic reticulum stress. In addition, inhibition of ROS reversed the apoptosis induced by SHI and ATO, and recovered the activation of endoplasmic reticulum stress, which revealed the vital role of ROS in the synergism. Moreover, HepG2 xenograft tumor growth in nude mice was more effectively inhibited by combined treatment with SHI and ATO. These data suggest that the combination of SHI with ATO presents a promising therapeutic approach for the treatment of HCC.

MiR-155 and its functional variant rs767649 contribute to the susceptibility and survival of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) ranks the fourth common cancer and the third common cause of cancer mortality among Chinese population. The development of hepatocellular carcinoma (HCC) were confirmed to be involved in complex interactions between environmental and genetic factors. MicroRNAs (miRNAs) have been found to play an important role in tumorigenesis and metastasis. Emerging evidence suggested that upregulation of miR-155, one of the best characterized miRNAs, could serve as a promising marker for the diagnosis and prognosis of many cancers, except for HCC. In current we tested the hypothesis that functional variant rs767649 located in the flanking region of miR-155 gene contributes to the development and survival of HCC. We identified that functional variant rs767649 in miR-155 regulation region was associated with risk and survival of HCC. The minor allele of rs767649 was significantly associated with an increased risk of HCC (OR=1.23, 95% CI=1.11-1.36, P = 7.97×10-5). The genotype TT of rs767649 was significantly associated with a 1.94 fold poor survival of HCC (HR=1.94, 95% CI=1.01-3.79), while 1.15 fold for genotype AT (HR=1.15, 95% CI=1.06-1.25). Results showed that miR-155 was highly overexpressed in HCC tissues, compared with the adjacent normal tissues (P<0.001). The allele T contributes to higher expression of miR-155 in both the HCC tissues and the adjacent non-tumor tissues (P< 0.01). Our findings suggested that miR-155 and its functional variant rs767649 might contribute to the increased risk and poor prognosis of HCC, highlighting the importance of miR-155 in the prevention and prognosis of HCC.

High Glucose-Induced PC12 Cell Death by Increasing Glutamate Production and Decreasing Methyl Group Metabolism

Objective. High glucose- (HG-) induced neuronal cell death is responsible for the development of diabetic neuropathy. However, the effect of HG on metabolism in neuronal cells is still unclear. Materials and Methods. The neural-crest derived PC12 cells were cultured for 72 h in the HG (75 mM) or control (25 mM) groups. We used NMR-based metabolomics to examine both intracellular and extracellular metabolic changes in HG-treated PC12 cells. Results. We found that the reduction in intracellular lactate may be due to excreting more lactate into the extracellular medium under HG condition. HG also induced the changes of other energy-related metabolites, such as an increased succinate and creatine phosphate. Our results also reveal that the synthesis of glutamate from the branched-chain amino acids (isoleucine and valine) may be enhanced under HG. Increased levels of intracellular alanine, phenylalanine, myoinositol, and choline were observed in HG-treated PC12 cells. In addition, HG-induced decreases in intracellular dimethylamine, dimethylglycine, and 3-methylhistidine may indicate a downregulation of methyl group metabolism. Conclusions. Our metabolomic results suggest that HG-induced neuronal cell death may be attributed to a series of metabolic changes, involving energy metabolism, amino acids metabolism, osmoregulation and membrane metabolism, and methyl group metabolism.

125 I brachytherapy of locally advanced non-small-cell lung cancer after one cycle of first-line chemotherapy：a comparison with best supportive care

Objectives The objective of this study was to assess the efficacy of computed tomography (CT)-guided 125I brachytherapy alone in improving the survival and quality of life of patients with unresectable locally advanced non-small-cell lung cancer (NSCLC) after one cycle of first-line chemotherapy. Patients and methods Sixteen patients with locally advanced NSCLC were treated with CT-guided 125I brachytherapy after one cycle of first-line chemotherapy (group A). Sixteen patients who received only best supportive care (group B) were matched up with the patients in group A. Primary end point included survival, and secondary end point included assessment of safety, effectiveness of CT-guided 125I brachytherapy, and improvement in the quality of life. Results The two groups were well balanced in terms of age, disease histology, tumor stage, tumor location, and performance status (P>0.05). The median follow-up time was 16 months (range, 3–30). The total tumor response rate was 75.0% in group A, which was significantly higher than that in group B (0.0%) (P<0.01). The median progression-free survival time was 4.80 months for patients in group A and 1.35 months for patients in group B (P<0.001). Kaplan–Meier survival analysis showed that the median survival time of group A was 9.4±0.3 months versus 8.4±0.1 months in group B (P=0.013). Tumor-related symptoms of patients were significantly relieved, and the quality of life was markedly improved in group A than in group B. Conclusion CT-guided 125I brachytherapy improved the survival of patients with locally advanced NSCLC and quality of life after one cycle of first-line chemotherapy compared with best supportive care.