The transcription factors aryl hydrocarbon receptor and MYC cooperate in the regulation of cellular metabolism.

The transcription factor AHR (aryl hydrocarbon receptor) drives the expression of genes involved in detoxification pathways in cells exposed to pollutants and other small molecules. Moreover, AHR supports transcriptional programs that promote ribosome biogenesis and protein synthesis in cells stimulated to proliferate by the oncoprotein MYC. Thus, AHR is necessary for the proliferation of MYC-overexpressing cells. To define metabolic pathways in which AHR cooperates with MYC in supporting cell growth, here we used LC-MS-based metabolomics to examine the metabolome of MYC-expressing cells upon AHR knockdown. We found that AHR knockdown reduced lactate, S-lactoylglutathione, N-acetyl-l-alanine, 2-hydroxyglutarate, and UMP levels. Using our previously obtained RNA sequencing data, we found that AHR mediates the expression of the UMP-generating enzymes dihydroorotate dehydrogenase (quinone) (DHODH) and uridine monophosphate synthetase (UMPS), as well as lactate dehydrogenase A (LDHA), establishing a mechanism by which AHR regulates lactate and UMP production in MYC-overexpressing cells. AHR knockdown in glioblastoma cells also reduced the expression of LDHA (and lactate), DHODH, and UMPS but did not affect UMP levels, likely because of compensatory mechanisms in these cells. Our results indicate that AHR contributes to the regulation of metabolic pathways necessary for the proliferation of transformed cells.

Evaluation of testicular glycogen storage, FGF21 and LDH expression and physiological parameters of sperm in hyperglycemic rats treated with hydroalcoholic extract of Securigera Securidaca seeds, and Glibenclamide.

Structural and physiological changes in sperm and semen parameters reduce fertility in diabetic patients. Securigera Securidaca (S. Securidaca) seed is a herbal medicine with hypoglycemic, antioxidant, and anti-hypertensive effects. The question now is whether this herbal medicine improves fertility in diabetic males. The study aimed to evaluate the effects of hydroalcoholic extract of S. Securidaca seeds (HESS), glibenclamide and a combination of both on fertility in hyperglycemic rats by comparing histological and some biochemical changes in testicular tissue and sperm parameters. The treatment protocol included administration of three doses of HESS and one dose of glibenclamide, as well as treatment with both in diabetic Wistar diabetic rats and comparison of the results with untrated groups. The quality of the testicular tissue as well as histometric parameters and spermatogenesis indices were evaluated during histopathological examination. Epididymal sperm analysis including sperm motility, viability, abnormalities, maturity, and chromatin structure were studied. The effect of HESS on the expression of LDH and FGF21 genes and tissue levels of glycogen, lactate, and total antioxidant capacity in testicular tissue was investigated and compared with glibenclamide. HESS improved sperm parameters in diabetic rats but showed little restorative effect on damaged testicular tissue. In this regard, glibenclamide was more effective than the highest dose of HESS and its combination with HESS enhanced its effectiveness so that histological tissue characteristics and sperm parameters were were comparable to those of healthy rats. The expression level of testicular FGF21 gene increased in diabetic rats, which intensified after treatment with HESS as well as glibenclamide. The combination of HESS and glibenclamide restored the expression level of testicular LDH gene, as well as tissue storage of glycogen, lactate and LDH activity, and serum testosterone to the levels near healthy control. S. Securidaca seeds can be considered as an effective supplement in combination with hypoglycemic drugs to prevent infertility complications in diabetes.

Contemporary Perspectives on the Warburg Effect Inhibition in Cancer Therapy.

In the 1920s, Otto Warburg observed the phenomenon of altered glucose metabolism in cancer cells. Although the initial hypothesis suggested that the alteration resulted from mitochondrial damage, multiple studies of the subject revealed a precise, multistage process rather than a random pattern. The phenomenon of aerobic glycolysis emerges not only from mitochondrial abnormalities common in cancer cells, but also results from metabolic reprogramming beneficial for their sustenance. The Warburg effect enables metabolic adaptation of cancer cells to grow and proliferate, simultaneously enabling their survival in hypoxic conditions. Altered glucose metabolism of cancer cells includes, inter alia, qualitative and quantitative changes within glucose transporters, enzymes of the glycolytic pathway, such as hexokinases and pyruvate kinase, hypoxia-inducible factor, monocarboxylate transporters, and lactate dehydrogenase. This review summarizes the current state of knowledge regarding inhibitors of cancer glucose metabolism with a focus on their clinical potential. The altered metabolic phenotype of cancer cells allows for targeting of specific mechanisms, which might improve conventional methods in anti-cancer therapy. However, several problems such as drug bioavailability, specificity, toxicity, the plasticity of cancer cells, and heterogeneity of cells in tumors have to be overcome when designing therapies based on compounds targeted in cancer cell energy metabolism.

Purifying and Characterizing Bacterially Expressed Soluble Lactate Dehydrogenase from Plasmodium knowlesi for the Development of Anti-Malarial Drugs.

Plasmodium lactate dehydrogenase (pLH) is one of the enzymes in glycolysis with potential target for chemotherapy. This study aimed to clone, overexpress and characterize soluble recombinant lactate dehydrogenase from Plasmodium knowlesi in a bacterial system. Synthetic P. knowlesi lactate dehydrogenase (Pk-LDH) gene was cloned into pET21a expression vector, transformed into Escherichia coli strain BL21 (DE3) expression system and then incubated for 18 h, 20 °C with the presence of 0.5 mM isopropyl ß-d-thiogalactoside in Terrific broth supplemented with Magnesium sulfate, followed by protein purifications using Immobilized Metal Ion Affinity Chromatography and size exclusion chromatography (SEC). Enzymatic assay was conducted to determine the activity of the enzyme. SDS-PAGE analysis revealed that protein of 34 kDa size was present in the soluble fraction. In SEC, a single peak corresponding to the size of Pk-LDH protein was observed, indicating that the protein has been successfully purified. From MALDI-TOF analysis findings, a peptide score of 282 was established, which is significant for lactate dehydrogenase from P. knowlesi revealed via MASCOT analysis. Secondary structure analysis of CD spectra indicated 79.4% α helix and 1.37% ß strand structure. Specific activity of recombinant Pk-LDH was found to be 475.6 U/mg, confirming the presence of active protein. Soluble Pk-LDH that is biologically active was produced, which can be used further in other malaria studies.

Ribosomal protein S3 selectively affects colon cancer growth by modulating the levels of p53 and lactate dehydrogenase.

Ribosomal protein S3 (RPS3) is a component of the 40S ribosomal subunit. It is known to function in ribosome biogenesis and as an endonuclease. RPS3 has been shown to be over expressed in colon adenocarcinoma but its role in colon cancer is still unknown. In this study, we aim at determining the expression levels of RPS3 in a colon cancer cell line Caco-2 compared to a normal colon mucosa cell line NCM-460 and study the effects of targeting this protein by siRNA on cellular behavior. RPS3 was found to be expressed in both cell lines. However, siRNA treatment showed a more protruding effect on Caco-2 cells compared to NCM-460 cells. RPS3 knockdown led to a significant decrease in the proliferation, survival, migration and invasion and an increase in the apoptosis of Caco-2 cells. Western blot analysis demonstrated that these effects correlated with an increase in the level of the tumor suppressor p53 and a decrease in the level and activity of lactate dehydrogenase (LDH), an enzyme involved in the metabolism of cancer cells. No significant effect was shown in normal colon NCM-460 cells. Targeting p53 by siRNA did not affect RPS3 levels indicating that p53 may be a downstream target of RPS3. However, the concurrent knockdown of RPS3 and p53 showed no change in LDH level in Caco-2 cells suggesting an interesting interplay among the three proteins. These findings might present RPS3 as a selective molecular marker in colon cancer and an attractive target for colon cancer therapy.

Di-2-ethylhexyl phthalate (DEHP) induces apoptosis of mouse HT22 hippocampal neuronal cells via oxidative stress.

Di-2-ethylhexyl phthalate (DEHP) has been widely used as a plasticizer in industry and can affect memory; however, the underlying mechanism remains unclear. In the present study, mouse HT22 cells, an immortalized hippocampal neuronal cell line, was utilized as an in vitro model. We showed that DEHP dramatically inhibited cell viability and increased lactate dehydrogenase (LDH) release from the cells in a dose-dependent manner, suggesting that DEHP could cause cytotoxicity of mouse HT22 cells. The protein levels of cleaved Caspase-8, cleaved Caspase-3, and Bax markedly increased in the DEHP-treated cells, whereas there was a significant decrease in the Bcl-2 protein level, implying that DEHP could induce apoptosis of mouse HT22 cells. DEHP exposure significantly increased the content of malondialdehyde, whereas it markedly decreased the level of glutathione and the activities of glutathione peroxidase and superoxide dismutase, suggesting that DEHP induced oxidative stress of the cells. Compared with the DEHP-treated group, the inhibition of cell viability and the release of LDH were rescued in the N-acetyl-l-cysteine plus DEHP group. Furthermore, inhibition of oxidative stress could rescue the induction of apoptosis by DEHP. Collectively, our results indicated that DEHP could induce apoptosis of mouse HT22 cells via oxidative stress.

Lactic Acid Downregulates Viral MicroRNA To Promote Epstein-Barr Virus-Immortalized B Lymphoblastic Cell Adhesion and Growth.

High plasma lactate is associated with poor prognosis of many malignancies, but its role in virally mediated cancer progression and underlying molecular mechanisms are unclear. Epstein-Barr virus (EBV), the first human oncogenic virus, causes several cancers, including B-cell lymphoma. Here, we report that lactate dehydrogenase A (LDH-A) expression and lactate production are elevated in EBV-immortalized B lymphoblastic cells, and lactic acid (LA; acidic lactate) at low concentration triggers EBV-infected B-cell adhesion, morphological changes, and proliferation in vitro and in vivo Moreover, LA-induced responses of EBV-infected B cells uniquely occurs in viral latency type III, and it is dramatically associated with the inhibition of global viral microRNAs, particularly the miR-BHRF1 cluster, and the high expression of SMAD3, JUN, and COL1A genes. The introduction of miR-BHRF1-1 blocks the LA-induced effects of EBV-infected B cells. Thus, this may be a novel mechanism to explain EBV-immortalized B lymphoblastic cell malignancy in an LA microenvironment.IMPORTANCE The tumor microenvironment is complicated, and lactate, which is created by cell metabolism, contributes to an acidic microenvironment that facilitates cancer progression. However, how LA operates in virus-associated cancers is unclear. Thus, we studied how EBV (the first tumor virus identified in humans; it is associated with many cancers) upregulates the expression of LDH-A and lactate production in B lymphoma cells. Elevated LA induces adhesion and the growth of EBV-infected B cells by inhibiting viral microRNA transcription. Thus, we offer a novel understanding of how EBV utilizes an acidic microenvironment to promote cancer development.

LDHA upregulation independently predicts poor survival in lung adenocarcinoma, but not in lung squamous cell carcinoma.

AIM: To investigate the potential prognostic value of LDHA in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). PATIENTS & METHODS: Molecular, clinicopathological and survival data in Cancer Genome Atlas-Lung Cancer were obtained for secondary analysis. RESULTS: LDHA expression was significantly upregulated in both LUAD and LUSC compared with normal lung tissues. LUSC tissues had even higher LDHA expression compared with LUAD tissues. Increased LDHA expression was an independent prognostic indicator in terms of overall survival (hazard ratio: 1.547, 95% CI: 1.253-1.911; p < 0.001) and recurrence-free survival (hazard ratio: 1.486, 95% CI: 1.161-1.900; p = 0.002) in LUAD, but not in LUSC. CONCLUSION: LDHA expression might only serve as an independent prognostic indicator of unfavorable overall survival and recurrence-free survival in LUAD, but not in LUSC.

Efficient production of (R)-(-)-2-hydroxy-4-phenylbutyric acid by recombinant Pichia pastoris expressing engineered D-lactate dehydrogenase from Lactobacillus plantarum with a single-site mutation.

(R)-2-hydroxy-4-phenylbutyric acid (R-HPBA) is a valuable intermediate for the synthesis of angiotensin-converting enzyme inhibitors. The asymmetric reduction of 2-oxo-4-phenylbutyric acid (OPBA) by oxidoreductases is an efficient approach for its synthesis. Here, we report a novel biocatalytic approach for asymmetric synthesis of R-HPBA using recombinant Pichia pastoris expressing the Tyr52Leu variant of D-lactate dehydrogenase (D-LDH) from Lactobacillus plantarum. The recombinant yeast cells showed impressive catalytic activity at a high concentration of NaOPBA (380 mM, 76 g/L) and achieved full conversion starting with 40 g/L NaOPBA or even at higher concentration. Under optimized reaction conditions (pH 7.5, 37 °C, and 2% glucose), a full conversion with > 95% reaction yield and ~ 100% product enantiomeric excess (ee) was achieved for the preparation of R-HPBA on a 2-g scale. The findings of this study promote both the biotransformation of R-HPBA and an extension of the application of recombinant yeast as biocatalysts.

Exercise Inducible Lactate Dehydrogenase B Regulates Mitochondrial Function in Skeletal Muscle.

Lactate dehydrogenase (LDH) catalyzes the interconversion of pyruvate and lactate, which are critical fuel metabolites of skeletal muscle particularly during exercise. However, the physiological relevance of LDH remains poorly understood. Here we show that Ldhb expression is induced by exercise in human muscle and negatively correlated with changes in intramuscular pH levels, a marker of lactate production, during isometric exercise. We found that the expression of Ldhb is regulated by exercise-induced peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α). Ldhb gene promoter reporter studies demonstrated that PGC-1α activates Ldhb gene expression through multiple conserved estrogen-related receptor (ERR) and myocyte enhancer factor 2 (MEF2) binding sites. Transgenic mice overexpressing Ldhb in muscle (muscle creatine kinase (MCK)-Ldhb) exhibited increased exercise performance and enhanced oxygen consumption during exercise. MCK-Ldhb muscle was shown to have enhanced mitochondrial enzyme activity and increased mitochondrial gene expression, suggesting an adaptive oxidative muscle transformation. In addition, mitochondrial respiration capacity was increased and lactate production decreased in MCK-Ldhb skeletal myotubes in culture. Together, these results identified a previously unrecognized Ldhb-driven alteration in muscle mitochondrial function and suggested a mechanism for the adaptive metabolic response induced by exercise training.

Misconceptions regarding basic thermodynamics and enzyme kinetics have led to erroneous conclusions regarding the metabolic importance of lactate dehydrogenase isoenzyme expression.

Lactate dehydrogenase (LDH) catalyzes the interconversion of pyruvate and lactate involving the coenzyme NAD+ . Part of the foundation for the proposed shuttling of lactate from astrocytes to neurons during brain activation is the differential distribution of LDH isoenzymes between the two cell types. In this short review, we outline the basic kinetic properties of the LDH isoenzymes expressed in neurons and astrocytes, and argue that the distribution of LDH isoenzymes does not in any way govern directional flow of lactate between the two cellular compartments. The two main points are as follows. First, in line with the general concept of chemical catalysis, enzymes do not influence the thermodynamic equilibrium of a chemical reaction but merely the speed at which equilibrium is obtained. Thus, differential distribution of LDH isoenzymes with different kinetic parameters does not predict which cells are producing and which are consuming lactate. Second, the thermodynamic equilibrium of the reaction is toward the reduced substrate (i.e., lactate), which is reflected in the concentrations measured in brain tissue, suggesting that the reaction is at near-equilibrium at steady state. To conclude, the cellular distribution of LDH isoenzymes is of little if any consequence in determining any directional flow of lactate between neurons and astrocytes. © 2017 Wiley Periodicals, Inc.

Expression of lactate dehydrogenase C correlates with poor prognosis in renal cell carcinoma.

Lactate dehydrogenase C is an isoenzyme of lactate dehydrogenase and a member of the cancer-testis antigens family. In this study, we aimed to investigate the expression and functional role of lactate dehydrogenase C and its basic mechanisms in renal cell carcinoma. First, a total of 133 cases of renal cell carcinoma samples were analysed in a tissue microarray, and Kaplan-Meier survival curve analyses were performed to investigate the correlation between lactate dehydrogenase C expression and renal cell carcinoma progression. Lactate dehydrogenase C protein levels and messenger RNA levels were significantly upregulated in renal cell carcinoma tissues, and the patients with positive lactate dehydrogenase C expression had a shorter progression-free survival, indicating the oncogenic role of lactate dehydrogenase C in renal cell carcinoma. In addition, further cytological experiments demonstrated that lactate dehydrogenase C could prompt renal cell carcinoma cells to produce lactate, and increase metastatic and invasive potential of renal cell carcinoma cells. Furthermore, lactate dehydrogenase C could induce the epithelial-mesenchymal transition process and matrix metalloproteinase-9 expression. In summary, these findings showed lactate dehydrogenase C was associated with poor prognosis in renal cell carcinoma and played a pivotal role in the migration and invasion of renal cell carcinoma cells. Lactate dehydrogenase C may act as a novel biomarker for renal cell carcinoma progression and a potential therapeutic target for the treatment of renal cell carcinoma.

White shrimp Litopenaeus vannamei recombinant lactate dehydrogenase: Biochemical and kinetic characterization.

Shrimp lactate dehydrogenase (LDH) is induced in response to environmental hypoxia. Two protein subunits deduced from different transcripts of the LDH gene from the shrimp Litopenaeus vannamei (LDHvan-1 and LDHvan-2) were identified. These subunits are expressed by alternative splicing. Since both subunits are expressed in most tissues, the purification of the enzyme from the shrimp will likely produce hetero LDH containing both subunits. Therefore, the aim of this study was to overexpress, purify and characterize only one subunit as a recombinant protein, the LDHvan-2. For this, the cDNA from muscle was cloned and overexpressed in E. coli as a fusion protein containing an intein and a chitin binding protein domain (CBD). The recombinant protein was purified by chitin affinity chromatography column that retained the CBD and released solely the full and active LDH. The active protein appears to be a tetramer with molecular mass of approximately 140 kDa and can use pyruvate or lactate as substrates, but has higher specific activity with pyruvate. The enzyme is stable between pH 7.0 to 8.5, and between 20 and 50 °C with an optimal temperature of 50 °C. Two pKa of 9.3 and 6.6, and activation energy of 44.8 kJ/mol°K were found. The kinetic constants Km for NADH was 23.4 ± 1.8 µM, and for pyruvate was 203 ± 25 µM, while Vmax was 7.45 µmol/min/mg protein. The shrimp LDH that is mainly expressed in shrimp muscle preferentially converts pyruvate to lactate and is an important enzyme for the response to hypoxia.

Ribosomal readthrough at a short UGA stop codon context triggers dual localization of metabolic enzymes in Fungi and animals.

Translation of mRNA into a polypeptide chain is a highly accurate process. Many prokaryotic and eukaryotic viruses, however, use leaky termination of translation to optimize their coding capacity. Although growing evidence indicates the occurrence of ribosomal readthrough also in higher organisms, a biological function for the resulting extended proteins has been elucidated only in very few cases. Here, we report that in human cells programmed stop codon readthrough is used to generate peroxisomal isoforms of cytosolic enzymes. We could show for NAD-dependent lactate dehydrogenase B (LDHB) and NAD-dependent malate dehydrogenase 1 (MDH1) that translational readthrough results in C-terminally extended protein variants containing a peroxisomal targeting signal 1 (PTS1). Efficient readthrough occurs at a short sequence motif consisting of a UGA termination codon followed by the dinucleotide CU. Leaky termination at this stop codon context was observed in fungi and mammals. Comparative genome analysis allowed us to identify further readthrough-derived peroxisomal isoforms of metabolic enzymes in diverse model organisms. Overall, our study highlights that a defined stop codon context can trigger efficient ribosomal readthrough to generate dually targeted protein isoforms. We speculate that beyond peroxisomal targeting stop codon readthrough may have also other important biological functions, which remain to be elucidated.

Expression of the glycolytic enzymes enolase and lactate dehydrogenase during the early phase of Toxoplasma differentiation is regulated by an intron retention mechanism.

The intracellular parasite Toxoplasma gondii converts from a rapidly replicating tachyzoite form during acute infection to a quiescent encysted bradyzoite stage that persists inside long-lived cells during chronic infection. Bradyzoites adopt reduced metabolism and slow replication while waiting for an opportunity to recrudesce the infection within the host. Interconversion between these two developmental stages is characterized by expression of glycolytic isoenzymes that play key roles in parasite metabolism. The parasite genome encodes two isoforms of lactate dehydrogenase (LDH1 and LDH2) and enolase (ENO1 and ENO2) that are expressed in a stage-specific manner. Expression of different isoforms of these enzymes allows T. gondii to rapidly adapt to diverse metabolic requirements necessary for either a rapid replication of the tachyzoite stage or a quiescent lifestyle typical of the bradyzoites. Herein we identified unspliced forms of LDH and ENO transcripts produced during transition between these two parasite stages suggestive of an intron retention mechanism to promptly exchange glycolytic isoforms for rapid adaptation to environmental changes. We also identified key regulatory elements in the ENO transcription units, revealing cooperation between the ENO2 5'-untranslated region and the ENO2 intron, along with identifying a role for the ENO1 3'-untranslated region in stage-specific expression.

Equating salivary lactate dehydrogenase (LDH) with LDH-5 expression in patients with oral squamous cell carcinoma: An insight into metabolic reprogramming of cancer cell as a predictor of aggressive phenotype.

Oral squamous cell carcinoma (OSCC) is the sixth most common human malignancy. According to World Health Organization, oral cancer has been reported to have the highest morbidity and mortality and a survival rate of approximately 50 % at 5 years from diagnosis. This is attributed to the subjectivity in TNM staging and histological grading which may result in less than optimum treatment outcomes including tumour recurrence. One of the hallmarks of cancer is aerobic glycolysis also known as the Warburg effect. This glycolytic phenotype (hypoxic state) not only confers immortality to cancer cells, but also correlates with the belligerent behaviour of various malignancies and is reflected as an increase in the expression of lactate dehydrogenase 5 (LDH-5), the main isoform of LDH catalysing the conversion of pyruvate to lactate during glycolysis. The diagnostic role of salivary LDH in assessing the metabolic phenotype of oral cancer has not been studied. Since salivary LDH is mainly sourced from oral epithelial cells, any pathological changes in the epithelium should reflect diagnostically in saliva. Thus in our current research, we made an attempt to ascertain the biological behaviour and aggressiveness of OSCC by appraising its metabolic phenotype as indirectly reflected in salivary LDH activity. We found that salivary LDH can be used to assess the aggressiveness of different histological grades of OSCC. For the first time, an evidence of differing metabolic behaviour in similar histologic tumour grade is presented. Taken together, our study examines the inclusion of salivary LDH as potential diagnostic parameter and therapeutic index in OSCC.

Monitoring a 'metabolic shift' after surgical resection of oral squamous cell carcinomas by serum lactate dehydrogenase.

OBJECTIVES: Monitoring surgical removal of oral squamous cell carcinomas (OSCC) is being routinely performed through clinical and imaging follow-up. We analyzed the potential use of serum lactate, lactate dehydrogenase (LDH), and LDH isoenzymes (LDH 1-5) as biomarkers in blood for the monitoring of surgical removal of OSCC. MATERIALS AND METHODS: Serum lactate, LDH, and LDH isoenzymes (LDH 1-5) have been prospectively assessed in healthy individuals (n = 19), patients with OSCC (n = 34: primary OSCC, n = 32 and recurrent OSCC, n = 2) before surgery and after curative tumor resection (n = 26). LDHA and LDHB expressions were analyzed by immunohistochemistry (IHC) in the same OSCC tumor specimen. RESULTS: Positive LDHA tumor tissue expression measured by IHC (n = 34/34, 100%) was significantly associated with increased serum LDH-5 (n = 24/34, 71%, P = 0.0258) but weak significantly associated with increased total serum LDH (n = 23/34, 68%, P = 0.0592). Positive LDHB tumor tissue expression measured by IHC (n = 25/34, 74%) was significantly associated with increased total serum LDH (P = 0.0172). After surgery, serum LDH and LDH-5 isoenzyme significantly decreased and LDH-1 significantly increased in the aftercare. A significantly inverse correlation of LDHA with LDHB IHC scores was found (P < 0.0001). CONCLUSIONS: The association of LDHA and LDHB measured by IHC with serum LDH indicates that analyzing this enzyme could serve as a favorable 'liquid biopsy' (non-invasive diagnostic tool) for OSCC.

The progression from a lower to a higher invasive stage of bladder cancer is associated with severe alterations in glucose and pyruvate metabolism.

Cancer cells present a particular metabolic behavior. We hypothesized that the progression of bladder cancer could be accompanied by changes in cells glycolytic profile. We studied two human bladder cancer cells, RT4 and TCCSUP, in which the latter represents a more invasive stage. The levels of glucose, pyruvate, alanine and lactate in the extracellular media were measured by Proton Nuclear Magnetic Resonance. The protein expression levels of glucose transporters 1 (GLUT1) and 3 (GLUT3), monocarboxylate transporter 4 (MCT4), phosphofructokinase-1 (PFK1), glutamic-pyruvate transaminase (GPT) and lactate dehydrogenase (LDH) were determined. Our data showed that glucose consumption and GLUT3 levels were similar in both cell lines, but TCCSUP cells displayed lower levels of GLUT1 and PFK expression. An increase in pyruvate consumption, concordant with the higher levels of lactate and alanine production, was also detected in TCCSUP cells. Moreover, TCCSUP cells presented lower protein expression levels of GPT and LDH. These results illustrate that bladder cancer progression is associated with alterations in cells glycolytic profile, namely the switch from glucose to pyruvate consumption in the more aggressive stage. This may be useful to develop new therapies and to identify biomarkers for cancer progression.

Skeletal muscle PGC-1α controls whole-body lactate homeostasis through estrogen-related receptor α-dependent activation of LDH B and repression of LDH A.

The peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) controls metabolic adaptations. We now show that PGC-1α in skeletal muscle drives the expression of lactate dehydrogenase (LDH) B in an estrogen-related receptor-α-dependent manner. Concomitantly, PGC-1α reduces the expression of LDH A and one of its regulators, the transcription factor myelocytomatosis oncogene. PGC-1α thereby coordinately alters the composition of the LDH complex and prevents the increase in blood lactate during exercise. Our results show how PGC-1α actively coordinates lactate homeostasis and provide a unique molecular explanation for PGC-1α-mediated muscle adaptations to training that ultimately enhance exercise performance and improve metabolic health.

Expression pattern of glucose metabolism genes correlate with development rate of buffalo oocytes and embryos in vitro under low oxygen condition.

PURPOSE: This study evaluates the effect of low oxygen conditions (5 Vs 20%) on buffalo embryo development. Expression patterns of key glucose metabolism genes (HK, PFK, LDH, PDH, G6PDH and Glut1) were assessed in buffalo oocytes and embryos cultured at 5 and 20% oxygen and correlated with development rate. METHODS: Maturation rate was observed by determining MII stages by Aceto-orcein method and blastocyst formation was observed at 7 day post insemination (dpi). Expression levels of genes were determined by real time PCR in oocytes / embryos at 5 and 20% O2. RESULTS: Oocyte maturation and blastocyst formation rates were significantly higher at 5% O2 as compared to 20% O2 (P < 0.05). The expression pattern of glycolytic genes (HK, PFK and G6PDH) indicated that oocytes and embryos under 5% O2 tend to follow anaerobic glycolysis and pentose phosphate pathways to support optimum embryo development. Under 20% O2, oocytes and embryos had high expression of PDH indicating higher oxidative phosphorylation. Further, less G6PDH expression at 20% O2 was indicative of lower pentose phosphate activity. Higher expression of LDH was observed in oocytes and embryos under 20% O2 indicating sub-optimal culture conditions. High Glut1 activity was observed in the oocytes / embryos at 5% O2, indicative of high glucose uptake correlating with high expression of glycolytic genes. CONCLUSION: The expression patterns of glucose metabolism genes could be a valuable indicator of the development potential of oocytes and embryos. The study indicates the importance of reduced oxygen conditions for production of good quality embryos.