Metformin and phenformin deplete tricarboxylic acid cycle and glycolytic intermediates during cell transformation and NTPs in cancer stem cells

Metformin, a first-line diabetes drug linked to cancer prevention in retrospective clinical analyses, inhibits cellular transformation and selectively kills breast cancer stem cells (CSCs). Although a few metabolic effects of metformin and the related biguanide phenformin have been investigated in established cancer cell lines, the global metabolic impact of biguanides during the process of neoplastic transformation and in CSCs is unknown. Here, we use LC/MS/MS metabolomics (>200 metabolites) to assess metabolic changes induced by metformin and phenformin in an Src-inducible model of cellular transformation and in mammosphere-derived breast CSCs. Although phenformin is the more potent biguanide in both systems, the metabolic profiles of these drugs are remarkably similar, although not identical. During the process of cellular transformation, biguanide treatment prevents the boost in glycolytic intermediates at a specific stage of the pathway and coordinately decreases tricarboxylic acid (TCA) cycle intermediates. In contrast, in breast CSCs, biguanides have a modest effect on glycolytic and TCA cycle intermediates, but they strongly deplete nucleotide triphosphates and may impede nucleotide synthesis. These metabolic profiles are consistent with the idea that biguanides inhibit mitochondrial complex 1, but they indicate that their metabolic effects differ depending on the stage of cellular transformation.Altered metabolism is a hallmark of malignantly transformed cells. Cancer risk is linked to metabolic syndrome, a disease state that includes obesity, type 2 diabetes, high cholesterol, and atherosclerosis. Retrospective studies of type 2 diabetes patients treated with metformin, the most widely prescribed antidiabetic drug, show a strong correlation between drug intake and reduced tumor incidence or reduced cancer-related deaths (1–4).In the breast lineage, metformin inhibits growth of cancer cell lines (5–7), blocks transformation in a Src-inducible cell system (8, 9), and selectively inhibits the growth of cancer stem cells (CSCs) (8). As a consequence of its selective effects on CSCs, combinatorial therapy of metformin and standard chemotherapeutic drugs (doxorubicin, paclitaxel, and cisplatin) increases tumor regression and prolongs remission in mouse xenografts (8, 10). In addition, metformin can decrease the chemotherapeutic dose for prolonging tumor remission in xenografts involving multiple cancer types (10).Phenformin, a related biguanide and formerly used diabetes drug, acts as an anticancer agent in tumors including lung, lymphoma, and breast cancer with a greater potency than metformin. Phenformin mediates antineoplastic effects at a lower concentration than metformin in cell lines, a PTEN-deficient mouse model, breast cancer xenografts, and drug-induced mitochondrial impairment (11–14). The chemical similarities of these biguanides, as well as their similar effects in diabetes and cancer, have led to the untested assumption that phenformin is essentially a stronger version of metformin.In a Src-inducible model of cellular transformation and CSC formation, multiple lines of evidence suggest that metformin inhibits a signal transduction pathway that results in an inflammatory response (15). In the context of atherosclerosis, metformin inhibits NF-κB activation and the inflammatory response via a pathway involving AMP kinase (AMPK) and the tumor suppressor PTEN (16, 17). As metformin alters energy metabolism in diabetics, we speculated that metformin might block a metabolic stress response that stimulates the inflammatory pathway (15). However, very little is known about the metabolic changes that inhibit the inflammatory pathway.Previous studies on metformin-induced metabolic effects in cancer have focused on single metabolic alterations or pathways in already established cancer cell lines. Metformin leads to activation of AMPK, which plays a key role in insulin signaling and energy sensing (18). Metformin can reduce protein synthesis via mTOR inhibition (19). In addition, metformin may directly impair mitochondrial respiration through complex I inhibition and has been described to boost glycolysis as a compensation mechanism (14, 20). In this regard, lactic acidosis can be a side effect of metformin and phenformin treatment of diabetic patients, presumably because inhibition of complex I prevents NADH oxidation, thereby leading to a requirement for cytosolic NADH to be oxidized by the conversion of pyruvate to lactate. There is some knowledge about the metabolic effects of metformin (21, 22), but very little is known about the specific metabolic alterations linking biguanides to inhibition of neoplastic transformation.Here, we perform a metabolomic analysis on the effects of metformin and phenformin in a Src-inducible model of transformation and in CSCs. This inducible model permits an analysis of the transition from nontransformed to transformed cells in an isogenic cell system and hence differs from analyses of already established cancer cell lines. We studied CSCs to address why this population, which is resistant to standard chemotherapeutics and hypothesized to be a major reason for tumor recurrence, is selectively inhibited by metformin. Our results indicate the metabolic effects of metformin and phenformin are remarkably similar to each other, with only a few differences. Both biguanides dramatically decrease tricarboxylic acid (TCA) cycle intermediates in the early stages of transformation, and they inhibit the boost in select glycolytic intermediates that normally occurs with transformation along with increases in glycerol 3-phosphate and lactate, which are metabolites branching from glycolysis. Unexpectedly, in CSCs, biguanides have only marginal effects on glycolytic and TCA cycle metabolites, but they severely decrease nucleotide triphosphates. These detailed metabolic analyses provide independent support for the idea that metformin inhibits mitochondrial complex 1 (14, 20), and they indicate that the metabolic effects of biguanides depend on the stage of the cellular transformation.     

A randomized,controlled trial of aerobic exercise in combination with paroxetine in the treatment of panic disorder

Abstract

Objectives. Regular aerobic exercise (running) has been shown to be superior to a pill placebo in the treatment of panic disorder. Combined drug and exercise treatment has not been investigated in randomized controlled studies to date. Methods. This is a randomized, 10-week, controlled, parallel group, pilot study. A total of 75 outpatients with panic disorder with or without agoraphobia (DSM-IV and ICD-10) received either (1) exercise plus paroxetine 40 mg/day (n=21), (2) relaxation plus paroxetine (n=17), (3) exercise plus pill placebo (n=20), or (4) relaxation plus pill placebo (n=17). Changes in the Panic and Agoraphobia Scale (P&A), and the Clinical Global Impression Scale (CGI) underwent repeated measure analysis. Results. Effects sizes were large for all groups (d=1.53–3.87), however not significantly different. Paroxetine-treated patients were significantly more improved than placebo-treated patients. On the CGI, patients in the exercise groups (plus paroxetine or placebo) had a trend toward better improvement compared to relaxation (P=0.06). Response and remission rates were higher in the paroxetine compared to pill placebo groups. Conclusions. While paroxetine was superior to placebo, aerobic exercise did not differ from relaxation training in most efficacy measures.     

Physical function and fitness in long-term survivors of childhood leukaemia

Objective: To evaluate the physical function and fitness in survivors of childhood leukaemia 5–6 years after cessation of chemotherapy.

Materials and methods: Thirteen children (six boys and seven girls; mean age 15.5 years) who were treated for leukaemia were studied 5–6 years after cessation of therapy. Physical function and fitness were determined by anthropometry, motor performance, muscle strength, anaerobic and aerobic exercise capacity.

Results: On motor performance, seven of the 13 patients showed significant problems in the hand-eye co-ordination domain. Muscle strength only showed a significantly lower value in the mean strength of the knee extensors. The aerobic and the anaerobic capacity were both significantly reduced compared to reference values.

Conclusion: Even 5–6 years after cessation of childhood leukaemia treatment, there are still clear late effects on motor performance and physical fitness. Chemotherapy-induced neuropathy and muscle atrophies are probably the prominent cause for these reduced test results. Physical training might be indicated for patients surviving leukaemia to improve fitness levels and muscle strength.     

IGFBP-3 Mediates Metabolic Homeostasis During Hyperosmolar Stress in the Corneal Epithelium

PurposeThe insulin-like growth factor binding protein-3 (IGFBP-3) is a multifunctional secretory protein with well-known roles in cell growth and survival. Data in our laboratory suggest that IGFBP-3 may be functioning as a stress response protein in the corneal epithelium. The purpose of this study is to determine the role of IGFBP-3 in mediating the corneal epithelial cell stress response to hyperosmolarity, a well-known pathophysiological event in the development of dry eye disease.MethodsTelomerase-immortalized human corneal epithelial (hTCEpi) cells were used in this study. Cells were cultured in serum-free media with (growth) or without (basal) supplements. Hyperosmolarity was achieved by increasing salt concentrations to 450 and 500 mOsM. Metabolic and mitochondrial changes were assessed using Seahorse metabolic flux analysis and assays for mitochondrial calcium, polarization and mtDNA. Levels of IGFBP-3 and inflammatory mediators were quantified using ELISA. Cytotoxicity was evaluated using a lactate dehydrogenase assay. In select experiments, cells were cotreated with 500 ng/mL recombinant human (rh)IGFBP-3.ResultsHyperosmolar stress altered metabolic activity, shifting cells towards a respiratory phenotype. Hyperosmolar stress further altered mitochondrial calcium levels, depolarized mitochondria, decreased levels of ATP, mtDNA, and expression of IGFBP-3. In contrast, hyperosmolar stress increased production of the proinflammatory cytokines IL-6 and IL-8. Supplementation with rhIGFBP-3 abrogated metabolic and mitochondrial changes with only marginal effects on IL-8.ConclusionsThese findings indicate that IGFBP-3 is a critical protein involved in hyperosmolar stress responses in the corneal epithelium. These data further support a new role for IGFBP-3 in the control of cellular metabolism.     

Glucose Content and Efficiency of Glycolysis in Protected Ischemic Kidneys of Different Species

In ischemic canine kidneys protected by Bretschneider's HTK solution the glycolytic lactate production is limited by a low renal substrate content. However, for anaerobic energy supply ischemic organs depend on glycolysis. To evaluate the role of glycolysis in renal protection, the relationship between lactate production and anaerobic energy supply was examined in protected kidneys of dogs, sheep, and swine. Additionally, in canine kidneys an attempt was made to improve anaerobic energy provision by adding glucose to the protective solution. The results were as follows: (1) According to increasing lactate production from swine to dog to sheep, intraischemic ATP decay was delayed least in swine and most in sheep. (2) Glucose addition (10 mM) to the HTK solution roughly doubled the time for ATP to fall to 1 μmollg dry wt (t_Atp) in dogs. (3) The greater the lactate production in all three species, the lower the decrease in SAN (ATP + ADP + AMP) from 5 to 120 min of ischemia. (4) A glucose additive in the protective solution led to a significant (p >. 005) increase of SAN in dogs at 120 min of ischemia. A sufficient substrate supply seems to be an essential component of a reliable renal protection.     

Proteomic and metabolomic profiling reveals time-dependent changes in hippocampal metabolism upon paroxetine treatment and biomarker candidates

Most of the commonly used antidepressants block monoamine reuptake transporters to enhance serotonergic or noradrenergic neurotransmission. Effects besides or downstream of monoamine reuptake inhibition are poorly understood and yet presumably important for the drugs' mode of action. In the present study we aimed at identifying hippocampal cellular pathway alterations in DBA/2 mice using paroxetine as a representative Selective Serotonin Reuptake Inhibitor (SSRI). Furthermore we identified biomarker candidates for the assessment of antidepressant treatment effects in plasma. Hippocampal protein levels were compared between chronic paroxetine- and vehicle-treated animals using in vivo¹⁵N metabolic labeling combined with mass spectrometry. We also studied the time course of metabolite level changes in hippocampus and plasma using a targeted polar metabolomics profiling platform. In silico pathway analyses revealed profound alterations related to hippocampal energy metabolism. Glycolytic metabolite levels acutely increased while Krebs cycle metabolite levels decreased upon chronic treatment. Changes in energy metabolism were influenced by altered glycogen metabolism rather than by altered glycolytic or Krebs cycle enzyme levels. Increased energy levels were reflected by an increased ATP/ADP ratio and by increased ratios of high-to-low energy purines and pyrimidines. In the course of our analyses we also identified myo-inositol as a biomarker candidate for the assessment of antidepressant treatment effects in the periphery. This study defines the cellular response to paroxetine treatment at the proteome and metabolome levels in the hippocampus of DBA/2 mice and suggests novel SSRI modes of action that warrant consideration in antidepressant development efforts.     

Akt-Kv4.3-CaMKⅡ在有氧运动抑制压力负荷小鼠 心肌肥厚中的作用及其机制

目的 探讨丝氨酸/苏氨酸激酶（Akt）-离子通道Kv4.3（Kv4.3）-钙调素依赖性蛋白激酶Ⅱ（CaMKⅡ）信号 通路在有氧运动抑制压力负荷小鼠心肌肥厚中的作用及其机制。方法 60只实验小鼠均分为5组：假手术（SHAM） 组、主动脉缩窄手术（TAC）组、假手术+有氧运动（SHAM+E）组、主动脉缩窄术+有氧运动（TAC+E）组,主动脉缩窄术+ 有氧运动+ Akt抑制剂Perifosine（TAC+E+Peri）组。高分辨率小动物超声系统评价小鼠心功能及肥厚程度,麦胚凝集 素（WGA）染色检测心肌细胞横截面积;荧光定量PCR（RT-qPCR）检测ANP表达,Western blot检测蛋白心房钠尿肽 （ANP）、p-Akt、Kv4.3、p-CaMKⅡ表达水平。结果 与SHAM组相比,TAC促进心肌肥厚,恶化心功能（P＜0.01）。给 予有氧运动训练后,TAC+E组较TAC组小鼠心功能改善,心肌肥厚程度减轻（P＜0.01）。同时Western blot检测显示, TAC组较SHAM组p-Akt、Kv4.3表达降低,p-CaMKⅡ上调（P＜0.01）;TAC+E组p-Akt和Kv4.3表达较TAC小鼠增加, p-CaMKⅡ下调（P＜0.01）。而给予Akt抑制剂Perifosine后,相比于TAC+E组,TAC+E+Peri组心功能恶化、心肌肥厚 程度和ANP表达增加,心肌细胞横截面积增大,同时伴随Kv4.3表达降低、p-CaMKⅡ增高（P＜0.01）。结论 有氧运 动训练能够通过调节Akt-Kv4.3-CaMKⅡ信号通路抑制压力负荷心肌肥厚。     

有氧运动对自发性高血压大鼠心肌纤维化的影响及机制

摘要：目的 观察长期有氧运动对自发性高血压大鼠（SHR）心肌纤维化的影响,并探讨调控胶原代谢的信号分 子——转化生长因子-β（1 TGF-β1）、结缔组织生长因子（CTGF）、基质金属蛋白酶2（MMP-2）和组织金属蛋白酶抑制 物-2（TIMP-2）在其中的作用机制。方法 30只雄性SHR随机分为安静对照（SHR-RC）组和有氧运动（SHR-AT） 组,同时将15只Wistar-Kyoto大鼠作为正常血压对照（NC）组。NC组和SHR-RC组动物在鼠笼安静饲养,SHR-AT组 进行24周跑台训练。实验结束后利用无创血压仪测定尾动脉血压,超声心动术检测心脏结构与功能,Masson染色获 取心脏胶原容积分数（CVF）,实时荧光定量 PCR 检测心钠素（ANP）、脑钠素（BNP）和 β-肌球蛋白重链（β-MHC） mRNA表达量,Western blotting检测TGF-β1、CTGF、MMP-2［包括总MMP-2（72 ku）和活化型MMP-2（64 ku）］、TIMP- 2和α-平滑肌肌动蛋白（α-SMA）蛋白表达量。结果 与NC组比较,SHR-RC组大鼠心腔扩张同时室壁变薄,心脏 CVF 增加,心功能下降,ANP、BNP 和 β-MHC mRNA 以及 TGF-β1、CTGF、TIMP-2 和 α-SMA 蛋白表达量上调（P＜ 0.05）,活化型MMP-2蛋白表达量以及活化型MMP-2/TIMP-2比值下降（P＜0.05）;与SHR-RC组比较,SHR-AT组心 脏扩张减轻,心脏CVF下降,心功能增强,ANP、BNP和β-MHC mRNA以及α-SMA蛋白表达量下调,活化型MMP-2 蛋白表达量以及活化型 MMP-2/TIMP-2 比值增加（P＜0.05）,而 TGF-β1、CTGF 和 TIMP-2 蛋白表达量无明显变化 （P＞0.05）。结论 长期规律有氧运动能够改善SHR心肌纤维化,并延缓心脏重塑和心力衰竭进程,其机制与胶原 降解增加（但对胶原合成无影响）以及抑制成纤维细胞向成肌纤维细胞分化有关