1. Pasteur Effect~present of oxygen stops glycolysis-fermentation of glucose
2. Warburg Effect~cancer prefers aerobic glycolysis in the present of oxygen-fermentation of glucose
3. Glucose is necessary for stabilization of hypoxia-inducible factor
4. LDHA-lowering agent vitamin C
Lactate Metabolism and Cardiac Muscle
Lactate has two established functions in the metabolism of the heart. First, during aerobic metabolism lactate is a normal myocardial fuel, which during certain conditions (e.g., exercise) can account for the major part of the myocardial oxygen consumption. A supply of lactate appears to depend on competition with other myocardial fuels, especially free fatty acids. Secondly, during anaerobic metabolism, lactate production is viewed as part of the Pasteur effect, whereby anaerobiosis accelerates glucose uptake and glycolysis, and pyruvate, instead of entering the citrate cycle, forms lactate.
Lactate Metabolism and Cardiac Muscle | SpringerLink
Fafournoux P, Demigne C, Remesy C。
研究了L-乳酸和d -乳酸在大鼠肝细胞制剂中的摄取率和胞内与胞外的分配比。L-和d -乳酸的吸收明显依赖于被动扩散和载体介导的组分。L-乳酸高亲和载体的表观Km在1.8 mM范围内，乳酸同分异构体之间的相互竞争抑制表明L-乳酸和d -乳酸可能通过不同的载体进行运输。不同阴离子抑制乳酸的转运;丙酮酸是最有效的阴离子，而只有高浓度的酮体才有效。酸性细胞外pH值增加乳酸盐的摄取，这种作用在l -乳酸盐中更为明显。在低pH时，l -乳酸被浓缩进入肝细胞，但其对载体的亲和力似乎没有改变，这表明存在一个从细胞膜上的pH梯度获取能量的过程。在乳酸/H+的假设中，H+的亲和力不依赖于乳酸浓度，H+的表观Km对应的pH值为7.34。在预先装载丙酮酸或乳酸盐的细胞后，未观察到乳酸盐摄取的反式刺激。目前的数据表明，在生理浓度下，肝脏对乳酸的吸收可能主要是通过载体介导的，肝细胞膜的转运速率可能与代谢速率相当。
Carrier-mediated uptake of lactate in rat hepatocytes. Effects of pH and
possible mechanisms for L-lactate transport.
Fafournoux P, Demigné C, Rémésy C.
The rate of uptake and the distribution ratio between intra- and extracellular compartments of L- and D-lactate were studied in hepatocyte preparations from fed rats. L- and D-lactate uptake apparently depended on both passive diffusion and carrier-mediated components. The apparent Km of the high-affinity carrier for L-lactate was in the range of 1.8 mM. The reciprocal competitive inhibitions between isomers of lactate suggest that L- and D-lactate might be transported by distinct carriers. Lactate transport was inhibited by various anions; pyruvate was the most potent anion, whereas only high concentrations of ketone bodies were effective. Acidic extracellular pH enhanced lactate uptake, this effect being more pronounced for L-lactate. At low pH, L-lactate was concentrated into hepatocytes, but its affinity for the carrier appeared unchanged, suggesting the existence of a process gaining energy from the pH gradient across the cell membrane. In the hypothesis of a lactate/H+ symport, the affinity for H+ was not dependent on lactate concentration and the apparent Km for H+ corresponded to a pH of 7.34. No trans-stimulation of lactate uptake after prior loading of the cells with pyruvate or lactate was observed. The present data suggest that, at physiological concentrations, lactate uptake by the liver might be largely carrier-mediated and the rate of transport across the liver cell membrane may be of a magnitude relatively comparable to the rate of metabolism.
Uptake of l-lactate by cultured rat brain neurons
The uptake of l-lactate was investigated in neuronal primary cultures derived from embryonic rat brain with a radioactive tracer method. After preincubation of the cells in glucose-free buffer for 30 min, uptake increased with time for at least 10 min. A saturable component of uptake was found with half-maximal uptake at 10 mM lactate. This saturable component was abolished in the presence of 10 mM α-cyano-4-hydroxycinnamic acid. In addition, a non-saturable component dominated the uptake at high concentrations of lactate. Uptake was accelerated with decreasing pH, and was inhibited considerably by pyruvate. It is concluded that neurons are endowed with a lactate transport system which resembles in its properties the monocarboxylate carrier of peripheral tissues.
细胞呼吸速率通常由代谢活动决定，但如果细胞氧张力(PO2)低于一个临界值(通常为1-10 Torr)，则呼吸速率将受到O2可用性的限制。降低代谢活动和能量需求以应对O2可用性下降的能力可能会增加对O2供应减少的抵抗力。原代培养的大鼠肝细胞在O2张力控制下被分离出来。用胶原酶消化法获得细胞，以相同的细胞密度接种于对照组和实验组的营养培养基中。当PO2快速减少(100→0 Torr > 40 min)时，细胞对O2的吸收未减少，直到PO2降低到10 Torr以下。相比之下，当细胞PO2在数小时内降低时，当O2张力达到70 Torr时，明显降低了对O2的吸收。这些下降与ATP浓度的降低和NAD(P)H的增加有关，而与同一PO2下的快速缺氧细胞相比。在PO2浓度降低24小时后，未检测到细胞活力的丧失。呼吸速率的降低与乳酸产量的增加有关。恢复正常氧与立即恢复到正常水平有关。这些结果表明，肝细胞能够通过一种机制，即除了氧气供应限制外，线粒体功能受到抑制，从而在PO2持续适度减少的过程中，可逆地降低代谢活动和氧气需求。这种反应可能改变细胞对包括缺氧在内的生理应激的敏感性。
Oxygen conformance of cellular respiration in hepatocytes
Cellular respiratory rates are normally determined by metabolic activity, but become rate limited by O2 availability if the cell O2 tension (PO2) falls below a critical value (typically 1-10 Torr). An ability to reduce metabolic activity and energy demand in response to a falling O2 availability might confer an increased resistance to a diminished O2 supply. Isolated rat hepatocytes were studied in primary culture under controlled O2 tensions. Cells were obtained by collagenase digestion and seeded into nutritive media in control and experimental spinner flasks at identical cell densities. Cells subjected to rapid reduction in PO2 (100 → 0 Torr over <40 min) exhibited undiminished O2 uptake until PO2 fell below 10 Torr. By contrast, when cell PO2 was reduced over several hours, significant decreases in O2 uptake became evident at O2 tensions as high as 70 Torr. These decreases were associated with a reduction in ATP concentration and an increase in NAD(P)H, compared with rapidly deoxygenated cells at the same PO2. No loss in cell viability was detected after 24 h at reduced PO2. The decrease in respiratory rate was associated with an increased rate of lactic acid production relative to normoxic controls. Restoration of normoxia was associated with an immediate return of O2 uptake to control levels. These results demonstrate that hepatocytes are capable of reversibly decreasing metabolic activity and O2 demand during sustained moderate reductions in PO2, via a mechanism that appears to involve an inhibition of mitochondrial function other than O2 supply limitation. This response may alter cellular susceptibility to physiological stresses including hypoxia.
Oxygen conformance of cellular respiration in hepatocytes — Northwestern
Inhibitory effect of tumor cell–derived lactic acid on human T cells
Inhibitory effect of tumor cell–derived lactic acid on human T cells
A characteristic feature of tumors is high production of lactic acid due to enhanced glycolysis. Here, we show a positive correlation between lactate serum levels and tumor burden in cancer patients and examine the influence of lactic acid on immune functions in vitro. Lactic acid suppressed the proliferation and cytokine production of human cytotoxic T lymphocytes (CTLs) up to 95% and led to a 50% decrease in cytotoxic activity. A 24-hour recovery period in lactic acid–free medium restored CTL function. CTLs infiltrating lactic acid–producing multicellular tumor spheroids showed a reduced cytokine production. Pretreatment of tumor spheroids with an inhibitor of lactic acid production prevented this effect. Activated T cells themselves use glycolysis and rely on the efficient secretion of lactic acid, as its intracellular accumulation disturbs their metabolism. Export by monocarboxylate transporter-1 (MCT-1) depends on a gradient between cytoplasmic and extracellular lactic acid concentrations and consequently, blockade of MCT-1 resulted in impaired CTL function. We conclude that high lactic acid concentrations in the tumor environment block lactic acid export in T cells, thereby disturbing their metabolism and function. These findings suggest that targeting this metabolic pathway in tumors is a promising strategy to enhance tumor immunogenicity.
Inhibitory effect of tumor cell–derived lactic acid on human T cells | Blood
缺氧与后生动物的许多病理状态和正常生理状态有关。我们发现在缺氧状态下，由氧和乳酸调节蛋白NDRG家族成员3 (NDRG3)介导的乳酸依赖信号通路。氧通过PHD2/VHL系统在蛋白水平负调控NDRG3的表达，而长期缺氧过量产生的乳酸通过与NDRG3结合阻断其蛋白酶体降解。我们还发现稳定的NDRG3蛋白通过激活raferk通路促进缺氧条件下的血管生成和细胞生长。抑制细胞内乳酸产生可消除ndrg3介导的缺氧反应。因此，ndrg3 - rafe - erk轴为乳酸诱导的缺氧信号传导提供了遗传基础，这可用于针对缺氧诱导疾病的治疗方法的开发，以及促进我们对缺氧反应的正常生理机制的理解。[BMB报告2015;48 (6):301 - 302)
利用免疫沉淀分析和质谱联用，我们发现了一种新的phd2结合蛋白，NDRG3，其表达通过蛋白酶体途径在蛋白水平上被氧负调控。我们发现NDRG3的善意衬底PHD2 / VHL系统,特别是在294脯氨酸羟化(图1)。相比之下,积极NDRG3表达式是由乳酸,乳酸积累在缺氧的稍后阶段当绑定抑制NDRG3泛素化与VHL,随后通过破坏其交互块的蛋白酶体降解(图1)。然而,NDRG3并不依赖于低氧诱导因子mRNA表达的活动。
我们的研究结果证明了乳酸信号在缺氧中的作用及其遗传性质，这取决于ndrg3 -c- rafe - erk1 /2轴。这些发现表明,HIF-1α和NDRG3形成一种氧依赖性的监管链缺氧反应,分为两个时间阶段。在缺氧的早期阶段,HIF-1α蛋白积累,调节基因表达所必需的适应性反应包括早期代谢重编程,在后期阶段,差异乳酸生产积累NDRG3信号,激活Raf-ERK通路诱导反应所需应对长期缺氧。因此,乳酸信号和相应的生物反应似乎功能耦合HIF-1α-induced代谢重编程,采用NDRG3关键链接。在这方面,建议部分缺氧反应,特别是发生在缺氧的后阶段,迄今为止已归因于HIF-1α,可能,事实上,NDRG3-mediated乳酸直接控制下的信号。
NDRG3-mediated lactate signaling in hypoxia
Hypoxia is associated with many pathological conditions as well as the normal physiology of metazoans. We identified a lactate-dependent signaling pathway in hypoxia, mediated by the oxygen- and lactate-regulated protein NDRG family member 3 (NDRG3). Oxygen negatively regulates NDRG3 expression at the protein level via the PHD2/VHL system, whereas lactate, produced in excess under prolonged hypoxia, blocks its proteasomal degradation by binding to NDRG3. We also found that the stabilized NDRG3 protein promotes angiogenesis and cell growth under hypoxia by activating the Raf-ERK pathway. Inhibiting cellular lactate production abolishes NDRG3-mediated hypoxia responses. The NDRG3-Raf-ERK axis therefore provides the genetic basis for lactate-induced hypoxia signaling, which can be exploited for the development of therapies targeting hypoxia-induced diseases in addition to advancing our understanding of the normal physiology of hypoxia responses. [BMB Reports 2015; 48(6): 301-302]
Keywords: Hypoxia, Lactate signaling, NDRG3, HIF-independent hypoxia responses, PHD2/VHL pathway
Low oxygen (hypoxia) conditions are frequently observed in many aspects of normal physiology such as in cells of exercising muscle or actively growing embryonic/fetal tissues. Hypoxia is also intimately associated with many diseases such as cancer and inflammation. The presence of hypoxia has been positively correlated with poor prognosis of cancer patients. Hypoxic conditions induce various cellular responses in metazoans, including metabolic reprogramming, angiogenesis, and anti-apoptosis, which facilitate adaptation to and survival in the harsh environment. Hypoxia inducible factors (HIFs) play central roles in these processes by controlling the expression of genes involved in diverse aspects of hypoxia responses. However, growing evidence indicates that hypoxia has many aspects that are not explained by HIF-mediated mechanisms alone. For example, the inhibition of HIF-mediated pathways did not always prevent tumor growth. Also, angiogenesis was preserved when HIF1A was knocked-out in embryonic stem cells or colon cancer cells. Therefore, a role for other oxygen-regulated pathways that are, similar to HIF pathways, controlled by PHD enzymes has been suggested. However, the HIF-independent aspects of hypoxic signaling remain poorly understood.
Using an immunoprecipitation assay coupled to mass spectrometry, we identified a novel PHD2-binding protein, NDRG3, whose expression is negatively regulated by oxygen at the protein level via the proteasomal pathway. We found that NDRG3 is a bona fide substrate of the PHD2/VHL system, specifically hydroxylated at proline 294 (Fig. 1). In contrast, NDRG3 expression is positively regulated by lactate that accumulates at the later phase of hypoxia when lactate binding inhibits NDRG3 ubiquitination by disrupting its interaction with VHL and subsequently blocks the proteasomal degradation (Fig. 1). However, the mRNA expression of NDRG3 was not dependent on HIF activity.
NDRG3-mediated lactate signaling in hypoxia
A Lactate-Induced Response to Hypoxia: Cell
Overexpression of Pyruvate Kinase M2 in Tumor Tissues Is Associated with Poor
Prognosis in Patients with Hepatocellular Carcinoma | SpringerLink
Overexpression of Pyruvate Kinase M2 in Tumor Tissues Is
Associated with Poor Prognosis in Patients with Hepatocellular Carcinoma
Hepatocellular carcinoma (HCC) is one of the most common malignant tumors, with a high degree of malignancy and a poor prognosis. The aim of this study was to investigate the relationship between expression of pyruvate kinase M2 (PKM2) and prognosis in patients with HCC. The expression levels of PKM2 and PKM1 in 86 cases of HCC were detected by immunohistochemistry. An H score was used to evaluate the expression of PKM, and all patients were further divided into PKM high-expression and PKM low-expression groups. The relationship between PKM2 expression and the clinicopathological parameters and prognosis of patients were subsequently analyzed. Our data suggested that the expression level of PKM2 was significantly higher in HCC tissues than in adjacent tissues and the negatively expression of PKM1 in HCC tissues. Kaplan-Meier analysis revealed that PKM2 expression was strongly associated with survival in HCC patients (P = 0.001). The patients in the PKM2 high-expression group had significantly shorter survival times than the patients in the PKM2 low-expression group (hazard ratio for death, 2.358; 95% confidence interval [1.156, 4.812]; P = 0.018). In conclusion, these data indicate that PKM2 expression in HCC tissue samples can be used as a prognostic factor for patients with HCC and that high PKM2 expression is correlated with a poor prognosis in HCC patients.
Overexpression of Pyruvate Kinase M2 in Tumor Tissues Is Associated with Poor Prognosis in Patients with Hepatocellular Carcinoma | SpringerLink
Oncotarget | Overexpression of PKM2 promotes mitochondrial
fusion through attenuated p53 stability
M2-type pyruvate kinase (PKM2) contributes to the Warburg effect. However, it remains unknown as to whether PKM2 has an inhibitory effect on mitochondrial function. We report in this work that PKM2 overexpression inhibits the expression of Drp1 and results in the mitochondrial fusion. The ATP production was found to be decreased, the mtDNA copy number elevated and the expression level of electron transport chain (ETC) complex I, III, V depressed in PKM2 overexpressed cells. PKM2 overexpression showed a decreased p53 protein level and a shorter p53 half-life. In contrast, PKM2 knockdown resulted in increased p53 expression and prolonged half-life of p53. PKM2 could directly bind with both p53 and MDM2 and promote MDM2-mediated p53 ubiquitination. The dimeric PKM2 significantly suppressed p53 expression compared with the other PKM2 mutants. The reverse relationship between PKM2 and Drp1 was further confirmed in a large number of clinical samples. Taken together, the present results highlight a new mechanism that link PKM2 to mitochondrial function, based on p53-Drp1 axis down regulation, revealing a novel therapeutic target in patients with abnormal mitochondria.
Oncotarget | Overexpression of PKM2 promotes mitochondrial fusion through
attenuated p53 stability
ClinIcal Investigation. 2019 Mar 1;129(3):1030-1046. doi: 10.1172/JCI121685.
Epub 2019 Jan 28.
Stress-induced epinephrine enhances lactate dehydrogenase A and promotes breast cancer stem-like cells.
Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China.
State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China.
CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
Center for Molecular Medicine, School of Life Science and Biotechnology, Dalian University of Technology, Dalian, China.
Department of Oncology, The First Affiliated Hospital of Dalian Medical University, Dalian, China.
Shanghai Information Center for Life Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
State Key Laboratory of Proteomics, National Center of Protein Sciences, Beijing Institute of Lifeomics, Beijing, China.
Department of Molecular and Cellular Biochemistry, Markey Cancer Center, University of Kentucky, College of Medicine, Lexington, Kentucky, USA.
Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai, China.
Department of Surgery and Cancer, Imperial College London, London, United Kingdom.
Laboratory of Immunophysiology, Department of Animal Sciences, College of Agricultural, Consumer and Environmental Sciences, and Department of Pathology, College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Chronic stress triggers activation of the sympathetic nervous system and drives malignancy. Using an immunodeficient murine system, we showed that chronic stress-induced epinephrine promoted breast cancer stem-like properties via lactate dehydrogenase A-dependent (LDHA-dependent) metabolic rewiring. Chronic stress-induced epinephrine activated LDHA to generate lactate, and the adjusted pH directed USP28-mediated deubiquitination and stabilization of MYC. The SLUG promoter was then activated by MYC, which promoted development of breast cancer stem-like traits. Using a drug screen that targeted LDHA, we found that a chronic stress-induced cancer stem-like phenotype could be reversed by vitamin C. These findings demonstrated the critical importance of psychological factors in promoting stem-like properties in breast cancer cells. Thus, the LDHA-lowering agent vitamin C can be a potential approach for combating stress-associated breast cancer.
临床调查。 2019三月1; 129（3）：1030-1046。 doi：10.1172 / JCI121685。 Epub 2019一月28。
Stress-induced epinephrine enhances lactate dehydrogenase A and promotes breast cancer stem-like cells. - PubMed - NCBI
Regeneron, Sanofi Cite Progress in Pursuing Eosinophilic Esophagitis Indication for Dupixent