Galloflavin suppresses lactate dehydrogenase activity and causes MYC downregulation in Burkitt lymphoma cells through NAD/NADH-dependent inhibition of sirtuin-1

The role of lactate and lactylation in ischemic cardiomyopathy: Mechanisms and gene expression

Ischemic cardiomyopathy (ICM) is a significant global public health issue, with its pathophysiology encompassing atherosclerotic plaque formation, thrombosis, hypoperfusion, ischemic cell death, and left ventricular remodeling. Lactate is not only regarded as an energy metabolite but also acts as a signaling molecule that influences various physiological processes, regulating metabolism and muscle contraction. Lactylation, an emerging epigenetic modification, affects protein functionality and gene expression through the P300 enzyme. In ICM, lactate accumulation leads to pH imbalance and myocardial cell dysfunction, impacting cellular signaling. This paper will analyze the role of lactylation in ICM, focusing on coronary artery disease (ASCVD) and myocardial infarction (MI). It will also explore the differential expression and immunological characteristics of lactylation-related genes in normal and ICM tissues, providing potential targets for future research.

Energy metabolism in health and diseases

Energy metabolism is indispensable for sustaining physiological functions in living organisms and assumes a pivotal role across physiological and pathological conditions. This review provides an extensive overview of advancements in energy metabolism research, elucidating critical pathways such as glycolysis, oxidative phosphorylation, fatty acid metabolism, and amino acid metabolism, along with their intricate regulatory mechanisms. The homeostatic balance of these processes is crucial; however, in pathological states such as neurodegenerative diseases, autoimmune disorders, and cancer, extensive metabolic reprogramming occurs, resulting in impaired glucose metabolism and mitochondrial dysfunction, which accelerate disease progression. Recent investigations into key regulatory pathways, including mechanistic target of rapamycin, sirtuins, and adenosine monophosphate-activated protein kinase, have considerably deepened our understanding of metabolic dysregulation and opened new avenues for therapeutic innovation. Emerging technologies, such as fluorescent probes, nano-biomaterials, and metabolomic analyses, promise substantial improvements in diagnostic precision. This review critically examines recent advancements and ongoing challenges in metabolism research, emphasizing its potential for precision diagnostics and personalized therapeutic interventions. Future studies should prioritize unraveling the regulatory mechanisms of energy metabolism and the dynamics of intercellular energy interactions. Integrating cutting-edge gene-editing technologies and multi-omics approaches, the development of multi-target pharmaceuticals in synergy with existing therapies such as immunotherapy and dietary interventions could enhance therapeutic efficacy. Personalized metabolic analysis is indispensable for crafting tailored treatment protocols, ultimately providing more accurate medical solutions for patients. This review aims to deepen the understanding and improve the application of energy metabolism to drive innovative diagnostic and therapeutic strategies.

Crosstalk between lactate and tumor-associated immune cells: clinical relevance and insight

Lactate, which was traditionally viewed as a metabolic byproduct of anaerobic glycolysis, has emerged as a significant signaling molecule involved in the development of tumors. Current studies highlight its dual function, where it not only fuels tumor development but also modulates immune responses. Lactate has an effect on various tumor-associated immune cells, promoting immunosuppressive conditions that facilitate tumor growth and immune evasion. This phenomenon is strongly associated with the Warburg effect, a metabolic shift observed in many cancers that favors glycolysis over oxidative phosphorylation, resulting in elevated lactate production. Exploring the complex interplay between lactate metabolism and tumor immunity provides a novel understanding regarding the mechanisms of tumor immune evasion and resistance to therapies. This review discusses the unique biology of lactate in the TME, its impact on immune cell dynamics, and its potential as a tumor treatment target.

How lactate affects immune strategies in lymphoma

Tumor cells undergo metabolic reprogramming through shared pathways, resulting in a hypoxic, acidic, and highly permeable internal tumor microenvironment (TME). Lactate, once only regarded as a waste product of glycolysis, has an inseparable dual role with tumor immunity. It can not only provide a carbon source for immune cells to enhance immunity but also help the immune escape through a variety of ways. Lymphoma also depends on the proliferation signal of TME. This review focuses on the dynamic process of lactate metabolism and immune function changes in lymphoma and aims to comprehensively summarize and explore which genes, transcription factors, and pathways affect the biological changes and functions of immune cells. To deeply understand the complex and multifaceted role of lactate metabolism and immunity in lymphoma, the combination of lactate targeted therapy and classical immunotherapy will be a promising development direction in the future.

Lactate and lactylation in cardiovascular diseases: current progress and future perspectives

Cardiovascular diseases (CVDs) are often linked to structural and functional impairments, such as heart defects and circulatory dysfunction, leading to compromised peripheral perfusion and heightened morbidity risks. Metabolic remodeling, particularly in the context of cardiac fibrosis and inflammation, is increasingly recognized as a pivotal factor in the pathogenesis of CVDs. Metabolic syndromes further predispose individuals to these conditions, underscoring the need to elucidate the metabolic underpinnings of CVDs. Lactate, a byproduct of glycolysis, is now recognized as a key molecule that connects cellular metabolism with the regulation of cellular activity. The transport of lactate between different cells is essential for metabolic homeostasis and signal transduction. Disruptions to lactate dynamics are implicated in various CVDs. Furthermore, lactylation, a novel post-translational modification, has been identified in cardiac cells, where it influences protein function and gene expression, thereby playing a significant role in CVD pathogenesis. In this review, we summarized recent advancements in understanding the role of lactate and lactylation in CVDs, offering fresh insights that could guide future research directions and therapeutic interventions. The potential of lactate metabolism and lactylation as innovative therapeutic targets for CVD is a promising avenue for exploration.

Natural compounds as lactate dehydrogenase inhibitors: potential therapeutics for lactate dehydrogenase inhibitors-related diseases

Lactate dehydrogenase (LDH) is a crucial enzyme involved in energy metabolism and present in various cells throughout the body. Its diverse physiological functions encompass glycolysis, and its abnormal activity is associated with numerous diseases. Targeting LDH has emerged as a vital approach in drug discovery, leading to the identification of LDH inhibitors among natural compounds, such as polyphenols, alkaloids, and terpenoids. These compounds demonstrate therapeutic potential against LDH-related diseases, including anti-cancer effects. However, challenges concerning limited bioavailability, poor solubility, and potential toxicity must be addressed. Combining natural compounds with LDH inhibitors has led to promising outcomes in preclinical studies. This review highlights the promise of natural compounds as LDH inhibitors for treating cancer, cardiovascular, and neurodegenerative diseases.

Spotlight on New Therapeutic Opportunities for MYC-Driven Cancers

MYC can be considered to be one of the most pressing and important targets for the development of novel anti-cancer therapies. This is due to its frequent dysregulation in tumors and due to the wide-ranging impact this dysregulation has on gene expression and cellular behavior. As a result, there have been numerous attempts to target MYC over the last few decades, both directly and indirectly, with mixed results. This article reviews the biology of MYC in the context of cancers and drug development. It discusses strategies aimed at targeting MYC directly, including those aimed at reducing its expression and blocking its function. In addition, the impact of MYC dysregulation on cellular biology is outlined, and how understanding this can underpin the development of approaches aimed at molecules and pathways regulated by MYC. In particular, the review focuses on the role that MYC plays in the regulation of metabolism, and the therapeutic avenues offered by inhibiting the metabolic pathways that are essential for the survival of MYC-transformed cells.

SIRT1/P53 pathway is involved in the Arsenic induced aerobic glycolysis in hepatocytes L-02 cells

Arsenic is a known human carcinogen. Low doses of arsenic can induce cell proliferation, but the mechanism remains elusive. Aerobic glycolysis, also known as the Warburg effect, is one of the characteristics of tumour cells and rapidly proliferating cells. P53 is a tumour suppressor gene that has been shown to be a negative regulator of aerobic glycolysis. SIRT1 is a deacetylase that inhibits the function of P53. In this study, we found that P53 was involved in low dose of arsenic-induced aerobic glycolysis through regulating HK2 expression in L-02 cells. Moreover, SIRT1 not only inhibited P53 expression but also decreased the acetylation level of P53-K382 in arsenic-treated L-02 cells. Meanwhile, SIRT1 influenced the expression of HK2 and LDHA, which then promoted arsenic-induced glycolysis in L-02 cells. Therefore, our study demonstrated that the SIRT1/P53 pathway is involved in arsenic-induced glycolysis, thereby promoting cell proliferation, which provides theoretical basis for enriching the mechanism of arsenic carcinogenesis.

Targeted Epigenetic Interventions in Cancer with an Emphasis on Pediatric Malignancies

Over the past two decades, novel hallmarks of cancer have been described, including the altered epigenetic landscape of malignant diseases. In addition to the methylation and hyd-roxymethylation of DNA, numerous novel forms of histone modifications and nucleosome remodeling have been discovered, giving rise to a wide variety of targeted therapeutic interventions. DNA hypomethylating drugs, histone deacetylase inhibitors and agents targeting histone methylation machinery are of distinguished clinical significance. The major focus of this review is placed on targeted epigenetic interventions in the most common pediatric malignancies, including acute leukemias, brain and kidney tumors, neuroblastoma and soft tissue sarcomas. Upcoming novel challenges include specificity and potential undesirable side effects. Different epigenetic patterns of pediatric and adult cancers should be noted. Biological significance of epigenetic alterations highly depends on the tissue microenvironment and widespread interactions. An individualized treatment approach requires detailed genetic, epigenetic and metabolomic evaluation of cancer. Advances in molecular technologies and clinical translation may contribute to the development of novel pediatric anticancer treatment strategies, aiming for improved survival and better patient quality of life.

Prognostic value of lactate dehydrogenase in non-small cell lung cancer patients with brain metastases: a retrospective cohort study

BACKGROUND

At present, although there are some known molecular markers for the prognosis of non-small cell lung cancer (NSCLC) brain metastases, but there are still shortcomings in sensitivity and specificity. Lactate dehydrogenase (LDH) is one of the key enzymes involved in malignancy vital glycolytic pathway. Elevated serum LDH levels are reported significantly associated with a poor prognosis in various malignancies. However, there is currently no consensus regarding the prognostic value of LDH in NSCLC patients with brain metastases.

METHODS

We retrospectively analyzed 224 patients diagnosed with lung cancer brain metastases between January 2006 and June 2020 after excluding patients meeting combined with other malignancies and inaccurate clinical information. The LDH cutoff values were obtained using a restricted cubic spline (RCS) model, and the patients were divided into two groups according to the optimal cut-off value (180 U/L). 107 patients with LDH ≤180 (47.77%) and 117 patients with LDH >180 (52.23%) were identified. Univariate and multivariate logistic regression analyses were performed to identify the risk factors. The overall survival (OS) time was defined as the time from the first diagnosis of brain metastases to the last follow-up or death. Of the included patients, 147 survived and 77 died. The Kaplan-Meier method was used to illustrate the OS difference between the two groups. Finally, sensitivity analysis was employed to evaluate the robustness of the results.

RESULTS

The OS rate was significantly lower in the high LDH group versus the low LDH group (P=0.009). The median survival times of the high and low LDH groups were approximately 16 and 33 months, respectively. Multivariate analysis showed that high LDH was associated with a significantly worse OS [adjusted hazard ratio (aHR), 1.567; 95% confidence interval (CI): 1.058 to 2.32, P=0.025] with adjustment for covariables that P<0.05 in univariate analysis. Sensitivity analysis indicated that the results of this study are robust, despite potential unmeasured confounders.

CONCLUSIONS

High level of serum LDH indicates poor prognosis for patients with NSCLC brain metastases. This finding may provide useful prognostic information for patients and clinicians to choose more aggressive treatment strategies.

Natural products targeting human lactate dehydrogenases for cancer therapy: A mini review

Reprogramming cancer metabolism has become the hallmark of cancer progression. As the key enzyme catalyzing the conversion of pyruvate to lactate in aerobic glycolysis of cancer cells, human lactate dehydrogenase (LDH) has been a promising target in the discovery of anticancer agents. Natural products are important sources of new drugs. Up to now, some natural compounds have been reported with the activity to target LDH. To give more information on the development of LDH inhibitors and application of natural products, herein, we reviewed the natural compounds with inhibition of LDH from diverse structures and discussed the future direction of the discovery of natural LDH inhibitors for cancer therapy.

Lactate metabolism in human health and disease

The current understanding of lactate extends from its origins as a byproduct of glycolysis to its role in tumor metabolism, as identified by studies on the Warburg effect. The lactate shuttle hypothesis suggests that lactate plays an important role as a bridging signaling molecule that coordinates signaling among different cells, organs and tissues. Lactylation is a posttranslational modification initially reported by Professor Yingming Zhao’s research group in 2019. Subsequent studies confirmed that lactylation is a vital component of lactate function and is involved in tumor proliferation, neural excitation, inflammation and other biological processes. An indispensable substance for various physiological cellular functions, lactate plays a regulatory role in different aspects of energy metabolism and signal transduction. Therefore, a comprehensive review and summary of lactate is presented to clarify the role of lactate in disease and to provide a reference and direction for future research. This review offers a systematic overview of lactate homeostasis and its roles in physiological and pathological processes, as well as a comprehensive overview of the effects of lactylation in various diseases, particularly inflammation and cancer.

Targeting Energy Metabolism in Cancer Treatment

Cancer is the second most common cause of death worldwide after cardiovascular diseases. The development of molecular and biochemical techniques has expanded the knowledge of changes occurring in specific metabolic pathways of cancer cells. Increased aerobic glycolysis, the promotion of anaplerotic responses, and especially the dependence of cells on glutamine and fatty acid metabolism have become subjects of study. Despite many cancer treatment strategies, many patients with neoplastic diseases cannot be completely cured due to the development of resistance in cancer cells to currently used therapeutic approaches. It is now becoming a priority to develop new treatment strategies that are highly effective and have few side effects. In this review, we present the current knowledge of the enzymes involved in the different steps of glycolysis, the Krebs cycle, and the pentose phosphate pathway, and possible targeted therapies. The review also focuses on presenting the differences between cancer cells and normal cells in terms of metabolic phenotype. Knowledge of cancer cell metabolism is constantly evolving, and further research is needed to develop new strategies for anti-cancer therapies.

Voluntary wheel running behaviour as a tool to assess the severity in a mouse pancreatic cancer model

Laboratory animals frequently undergo routine experimental procedures such as handling, restraining and injections. However, as a known source of stress, these procedures potentially impact study outcome and data quality. In the present study, we, therefore, performed an evidence-based severity assessment of experimental procedures used in a pancreatic cancer model including surgical tumour induction and subsequent chemotherapeutic treatment via repeated intraperitoneal injections. Cancer cell injection into the pancreas was performed during a laparotomy under general anaesthesia. After a four-day recovery phase, mice received either drug treatment (galloflavin and metformin) or the respective vehicle substances via daily intraperitoneal injections. In addition to clinical scoring, an automated home-cage monitoring system was used to assess voluntary wheel running (VWR) behaviour as an indicator of impaired well-being. After surgery, slightly elevated clinical scores and minimal body weight reductions, but significantly decreased VWR behaviour were observed. During therapy, body weight declined in response to chemotherapy, but not after vehicle substance injection, while VWR activity was decreased in both cases. VWR behaviour differed between treatment groups and revealed altered nightly activity patterns. In summary, by monitoring VWR a high impact of repeated injections on the well-being of mice was revealed and substance effects on well-being were distinguishable. However, no differences in tumour growth between treatment groups were observed. This might be due to the severity of the procedures uncovered in this study, as exaggerated stress responses are potentially confounding factors in preclinical studies. Finally, VWR was a more sensitive indicator of impairment than clinical scoring in this model.

Auricularia auricula Melanin Protects against Alcoholic Liver Injury and Modulates Intestinal Microbiota Composition in Mice Exposed to Alcohol Intake

The potential effects of Auricularia auricula melanin (AAM) on the intestinal flora and liver metabolome in mice exposed to alcohol intake were investigated for the first time. The results showed that oral administration of AAM significantly reduced the abnormal elevation of serum total triglyceride (TG), cholesterol (TC), low density lipoprotein cholesterol (LDL-C), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and significantly inhibited hepatic lipid accumulation and steatosis in mice exposed to alcohol intake. Besides, the abnormally high levels of bile acids (BAs) and lactate dehydrogenase (LDH) in the liver of mice with alcohol intake were significantly decreased by AAM intervention, while the hepatic levels of glutathione (GSH) and superoxide dismutase (SOD) were appreciably increased. Compared with the model group, AAM supplementation significantly changed the composition of intestinal flora and up-regulated the levels of Akkermansia, Bifidobacterium, Romboutsia, Muribaculaceae, Lachnospiraceae_NK4A136_group, etc. Furthermore, liver metabolomics demonstrated that AAM had a significant regulatory effect on the composition of liver metabolites in mice with alcohol intake, especially the metabolites involved in phosphatidylinositol signaling system, ascorbate and aldarate metabolism, starch and sucrose metabolism, galactose metabolism, alpha-linolenic acid metabolism, glycolysis/gluconeogenesis, and biosynthesis of unsaturated fatty acids. At the gene level, AAM treatment regulated the mRNA levels of lipid metabolism and inflammatory response related genes in liver, including ACC-1, FASn, CPT-1, CD36, IFN-γ, LDLr and TNF-α. Conclusively, these findings suggest that AAM has potential beneficial effects on alleviating alcohol-induced liver injury and is expected to become a new functional food ingredient.

LDHA-Mediated Glycolytic Metabolism in Nucleus Pulposus Cells Is a Potential Therapeutic Target for Intervertebral Disc Degeneration

The intervertebral disc degeneration (IDD) is considered to be an initiator of a series of spinal diseases, among which changes in the nucleus pulposus (NP) are the most significant. NP cells reside in a microenvironment with a lack of blood vessels, hypoxia, and low glucose within the intervertebral disc. Due to the strong activity of HIF-1α, glycolysis is the main pathway for energy metabolism in NP cells. Our previous study found that higher SIRT1 expression is beneficial to delay the degeneration of NP cells. In order to find the downstream genes by which SIRT1 acts on NP cells, we used iTRAQ sequencing to detect the differences between degenerated NP cells overexpressing SIRT1 and a control group (human NP cells were derived from surgery) and found that the expression of LDHA changed in the same direction with SIRT1. This suggests that SIRT1 may delay the degeneration of NP cells by regulating glycolysis. We then used a Seahorse XFe24 analyzer to measure the bioenergetic parameters of NP cells and obtained three findings: (a) glycolysis is the main energy metabolism pathway in NP cells, (b) there is a large difference in ATP production between senescent cells and young cells, and (c) SIRT1 can regulate the production of ATP from glycolysis by regulating LDHA. We also found that SIRT1 in NP cells has a positive regulatory effect on c-Myc which is an upstream gene of LDHA. Through observing IDD-related indicators such as apoptosis, proliferation, senescence, and extracellular matrix, we found that SIRT1 can delay degeneration, and interference with c-Myc and LDHA, respectively, weakens the protective effect of SIRT1. Interfering with LDHA alone can also inhibit glycolysis and accelerate degeneration. Overall, we found that the inhibition of glycolysis in Np cells significantly affects their normal physiological functions and determined that LDHA is a potential therapeutic target for the treatment of IDD.

Targeting Cancer Metabolism and Current Anti-Cancer Drugs

Several studies have exploited the metabolic hallmarks that distinguish between normal and cancer cells, aiming at identifying specific targets of anti-cancer drugs. It has become apparent that metabolic flexibility allows cancer cells to survive during high anabolic demand or the depletion of nutrients and oxygen. Cancers can reprogram their metabolism to the microenvironments by increasing aerobic glycolysis to maximize ATP production, increasing glutaminolysis and anabolic pathways to support bioenergetic and biosynthetic demand during rapid proliferation. The increased key regulatory enzymes that support the relevant pathways allow us to design small molecules which can specifically block activities of these enzymes, preventing growth and metastasis of tumors. In this review, we discuss metabolic adaptation in cancers and highlight the crucial metabolic enzymes involved, specifically those involved in aerobic glycolysis, glutaminolysis, de novo fatty acid synthesis, and bioenergetic pathways. Furthermore, we also review the success and the pitfalls of the current anti-cancer drugs which have been applied in pre-clinical and clinical studies.

Chiral Pyridine-3,5-bis- (L-phenylalaninyl-L-leucinyl) Schiff Base Peptides as Potential Anticancer Agents: Design, Synthesis, and Molecular Docking Studies Targeting Lactate Dehydrogenase-A

A series of branched tetrapeptide Schiff bases 3–6 were designed and synthesized from corresponding tetrapeptide hydrazide 2 as a starting material.In vitroevaluation of the synthesized compounds 4–6 against breast MCF-7 carcinoma cells identified their excellent anticancer potency, with IC₅₀ ranging from 8.12 ± 0.14 to 17.55 ± 0.27 μM in comparison with the references, cisplatin and milaplatin (IC₅₀= 13.34 ± 0.11and 18.43 ± 0.13 μM, respectively). Furthermore, all derivatives demonstrated promising activity upon evaluation of theirin vitroandin vivosuppression of p53 ubiquitination and inhibition assessment for LDHA kinase. Finally, molecular docking studies were performed to predict the possible binding features of the potent derivatives within the ATP pocket of LDHA in an attempt to get a lead for developing a more potent LDHA inhibitor with anti-proliferative potency.

Synthesis and Molecular Docking of New Thiophene Derivatives as Lactate Dehydrogenase-A Inhibitors

BACKGROUND & OBJECTIVE

A series of novel derivatives possessing the thiophene moiety were synthesized using ethyl 5'-amino-2,3'-bithiophene-4'-carboxylate as the starting material.

METHODS

The new synthesized derivatives were screened as lactate dehydrogenase (LDH) inhibitors. LDH plays an important role in glucose metabolism in cancer cells and can affect tumor genesis and metastasis.

RESULTS

3-Substituted p-tolylthieno[2,3-d]pyrimidin-4(3H)-ones 4 were the most potent inhibitors in this study compared to Galloflavin reference drug.

CONCLUSION

Molecular docking studies on the Human Lactate Dehydrogenase active site were carried out on the synthesized compounds and the MolDock scores ranged between -127 to -171.

Symmetric molecules with 1,4-triazole moieties as potent inhibitors of tumour-associated lactate dehydrogenase-A

A series of symmetric molecules incorporating aryl or pyridyl moieties as central core and 1,4-substituted triazoles as a side bridge was synthesised. The new compounds were investigated as lactate dehydro-genase (LDH, EC 1.1.1.27) inhibitors. The cancer associated LDHA isoform was inhibited with IC50 = 117-174 µM. Seven compounds exhibited better LDHA inhibition (IC50 117-136 µM) compared to known LDH inhibitor - galloflavin (IC50 157 µM).

Synthesis of natural urolithin M6, a galloflavin mimetic, as a potential inhibitor of lactate dehydrogenase A

Glycolysis is the main route for energy production in tumors. LDH-A is a key enzyme of this process and its inhibition represents an attractive strategy to hamper cancer cell metabolism. Galloflavin is a reliable LDH-A inhibitor as previously identified by us; however, its poor physicochemical properties and chemical tractability render it unsuitable for further development. Therefore, a rational design was undertaken with the aim to reproduce the pharmacophore of galloflavin on simpler, potentially more soluble and synthetic accessible scaffolds. Following a process of structural simplification, natural urolithin M6 (UM6), which is an ellagitannin metabolite produced by gut microbiota, was identified as a putative galloflavin mimetic. In the present study, the synthesis of UM6 is described for the first time. An efficient synthetic pathway has been developed, which involved five steps from readily accessible starting materials. The key reaction steps, a Suzuki coupling and an intramolecular C-H oxygenation, have been optimized to improve the synthetic feasibility and provide the best conditions in terms of reaction time and yield. Moreover, this route would be suitable to obtain other analogs for SAR studies. Preliminary biological tests revealed that UM6 was able to smoothly reproduce the behavior of galloflavin, confirming that our approach was successful in providing a new and accessible structure in the search for new LDH-A inhibitors.

Targeting MYC Dependence by Metabolic Inhibitors in Cancer

MYC is a critical growth regulatory gene that is commonly overexpressed in a wide range of cancers. Therapeutic targeting of MYC transcriptional activity has long been a goal, but it has been difficult to achieve with drugs that directly block its DNA-binding ability. Additional approaches that exploit oncogene addiction are promising strategies against MYC-driven cancers. Also, drugs that target metabolic regulatory pathways and enzymes have potential for indirectly reducing MYC levels. Glucose metabolism and oxidative phosphorylation, which can be targeted by multiple agents, promote cell growth and MYC expression. Likewise, modulation of the signaling pathways and protein synthesis regulated by adenosine monophosphate-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) can also be an effective route for suppressing MYC translation. Furthermore, recent data suggest that metabolism of nucleotides, fatty acids and glutamine are exploited to alter MYC levels. Combination therapies offer potential new approaches to overcome metabolic plasticity caused by single agents. Although potential toxicities must be carefully controlled, new inhibitors currently being tested in clinical trials offer significant promise. Therefore, as both a downstream target of metabolism and an upstream regulator, MYC is a prominent central regulator of cancer metabolism. Exploiting metabolic vulnerabilities of MYC-driven cancers is an emerging research area with translational potential.

Lactate dehydrogenase inhibitors can reverse inflammation induced changes in colon cancer cells

The inflammatory microenvironment is an essential component of neoplastic lesions and can significantly impact on tumor progression. Besides facilitating invasive growth, inflammatory cytokines were also found to reprogram cancer cell metabolism and to induce aerobic glycolysis. Previous studies did not consider the possible contribution played in these changes by lactate dehydrogenase (LDH). The A isoform of LDH (LDH-A) is the master regulator of aerobic glycolysis; it actively reduces pyruvate and causes enhanced lactate levels in tumor tissues. In cancer cells, lactate was recently found to directly increase migration ability; moreover, when released in the microenvironment, it can facilitate matrix remodeling. In this paper, we illustrate that treatment of human colon adenocarcinoma cells with TNF-α and IL-17, two pro-inflammatory cytokines, modifies LDH activity, causing a shift toward the A isoform which results in increased lactate production. At the same time, the two cytokines appeared to induce features of epithelial-mesenchymal transition in the treated cells, such as reduction of E-cadherin levels and increased secretion of metalloproteinases. Noteworthy, oxamate and galloflavin, two inhibitors of LDH activity which reduce lactate production in cells, were found to relieve the inflammation-induced effects. These results suggest LDH-A and/or lactate as common elements at the cross-road between cancer cell metabolism, tumor progression and inflammation. At present, LDH inhibitors suitable for clinical use are actively searched as possible anti-proliferative agents; our data lead to hypothesize for these compounds a wider potential in anticancer treatment.

Lactate dehydrogenase inhibition: exploring possible applications beyond cancer treatment

Lactate dehydrogenase (LDH) inhibition is considered a worthwhile attempt in the development of innovative anticancer strategies. Unfortunately, in spite of the involvement of several research institutions and pharma-companies, the discovery of LDH inhibitors with drug-like properties seems a hardly resolvable challenge. While awaiting new advancements, in the present review we will examine other pathologic conditions characterized by increased glycolysis and LDH activity, which could potentially benefit from LDH inhibition. The rationale for targeting LDH activity in these contexts is the same justifying the LDH-based approach in anticancer therapy: because of the enzyme position at the end of glycolytic pathway, LDH inhibitors are not expected to hinder glucose metabolism of normal cells. Moreover, we will summarize the latest contributions in the discovery of enzyme inhibitors and try to glance over the reasons underlying the complexity of this research.

Influence of Altered NADH Metabolic Pathway on the Respiratory-deficient Mutant of Rhizopus oryzae and its L-lactate Production

Respiratory-deficient mutants of Rhizopus oryzae (R. oryzae) AS 3.3461 were acquired by ultraviolet (UV) irradiation to investigate changes in intracellular NADH metabolic pathway and its influence on the fermentation characteristics of the strain. Compared with R. oryzae AS 3.3461, the intracellular ATP level of the respiratory-deficient strain UV-1 decreased by 52.7 % and the glucose utilization rate rose by 8.9 %; When incubated for 36 h, the activities of phosphofructokinase (PFK), hexokinase (HK), and pyruvate kinase (PK) in the mutant rose by 74.2, 7.2, and 12.0 %, respectively; when incubated for 48 h, the intracellular NADH/NAD(+) ratio of the mutant rose by 14.6 %; when a mixed carbon source with a glucose/gluconic acid ratio of 1:1 was substituted to culture the mutant, the NADH/NAD(+) ratio decreased by 4.6 %; the ATP content dropped by 27.6 %; the lactate dehydrogenase (LDH) activity rose by 22.7 %; and the lactate yield rose by 11.6 %. These results indicated that changes to the NADH metabolic pathway under a low-energy charge level can effectively increase the glycolytic rate and further improve the yield of L-lactate of R. oryzae.

Lactate dehydrogenase inhibitors sensitize lymphoma cells to cisplatin without enhancing the drug effects on immortalized normal lymphocytes

Up-regulation of glycolysis, a well recognized hallmark of cancer cells, was also found to be predictive of poor chemotherapy response. This observation suggested the attempt of sensitizing cancer cells to conventional chemotherapeutic agents by inhibiting glucose metabolism. Lactate dehydrogenase (LDH) inhibition can be a way to hinder glycolysis of cancer cells without affecting the metabolism of normal tissues, which usually does not require this enzymatic activity. In this paper, we showed that two LDH inhibitors (oxamate and galloflavin) can increase the efficacy of cisplatin in cultured Burkitt's lymphoma (BL) cells and that this potentiating effect is not exerted in proliferating normal lymphocytes. This result was explained by the finding that in BL cells LDH inhibition induced reactive oxygen species (ROS) generation, which was not evidenced in proliferating normal lymphocytes. In BL cells treated with the association of cisplatin and LDH inhibitors, these ROS can be a further cause of DNA damage, to be added to that produced by cisplatin, leading to the failure of the response repair. At present LDH inhibitors suitable for clinical use are actively searched; our results can allow a better understanding of the potentiality of LDH as a possible target to develop innovative anticancer treatments.

Evaluation of the anti-tumor effects of lactate dehydrogenase inhibitor galloflavin in endometrial cancer cells

High rates of aerobic glycolysis represent a key mechanism by which endometrial cancer cells consume glucose as its primary energy source. The up-regulated glycolytic pathway is a common therapeutic target whose inhibition has implications for anti-tumor activity in cancer cells. The present study was aimed at evaluating the potential of a novel lactate dehydrogenase (LDH) inhibitor, Galloflavin, as a therapeutic agent for endometrial cancer. Our results revealed that Galloflavin effectively inhibited cell growth in endometrial cancer cell lines and primary cultures of human endometrial cancer through its involvement in multiple signaling pathways that regulate metabolism, cell cycle, apoptosis, cell stress and metastasis.

Inhibition of lactate dehydrogenase activity as an approach to cancer therapy

In the attempt of developing innovative anticancer treatments, growing interest has recently focused on the peculiar metabolic properties of cancer cells. In this context, LDH, which converts pyruvate to lactate at the end of glycolysis, is emerging as one of the most interesting molecular targets for the development of new inhibitors. In fact, because LDH activity is not needed for pyruvate metabolism through the TCA cycle, inhibitors of this enzyme should spare glucose metabolism of normal non-proliferating cells, which usually completely degrade the glucose molecule to CO2. This review is aimed at summarizing the available data on LDH biology in normal and neoplastic cells, which support the anticancer therapeutic approach based on LDH inhibition. These data encouraged pharmaceutical industries and academic institutions in the search of small-molecule inhibitors and promising candidates have recently been identified. The availability of inhibitors with drug-like properties will allow the evaluation in the near future of the real potential of LDH inhibition in anticancer treatment, also making the identification of the most responsive neoplastic conditions possible.

Interplay between sirtuins, MYC and hypoxia-inducible factor in cancer-associated metabolic reprogramming

In the early twentieth century, Otto Heinrich Warburg described an elevated rate of glycolysis occurring in cancer cells, even in the presence of atmospheric oxygen (the Warburg effect). Despite the inefficiency of ATP generation through glycolysis, the breakdown of glucose into lactate provides cancer cells with a number of advantages, including the ability to withstand fluctuations in oxygen levels, and the production of intermediates that serve as building blocks to support rapid proliferation. Recent evidence from many cancer types supports the notion that pervasive metabolic reprogramming in cancer and stromal cells is a crucial feature of neoplastic transformation. Two key transcription factors that play major roles in this metabolic reprogramming are hypoxia inducible factor-1 (HIF1) and MYC. Sirtuin-family deacetylases regulate diverse biological processes, including many aspects of tumor biology. Recently, the sirtuin SIRT6 has been shown to inhibit the transcriptional output of both HIF1 and MYC, and to function as a tumor suppressor. In this Review, we highlight the importance of HIF1 and MYC in regulating tumor metabolism and their regulation by sirtuins, with a main focus on SIRT6.

Identification of LDH-A as a therapeutic target for cancer cell killing via (i) p53/NAD(H)-dependent and (ii) p53-independent pathways

Most cancer cells use aerobic glycolysis to fuel their growth. The enzyme lactate dehydrogenase-A (LDH-A) is key to cancer's glycolytic phenotype, catalysing the regeneration of nicotinamide adenine dinucleotide (NAD(+)) from reduced nicotinamide adenine dinucleotide (NADH) necessary to sustain glycolysis. As such, LDH-A is a promising target for anticancer therapy. Here we ask if the tumour suppressor p53, a major regulator of cellular metabolism, influences the response of cancer cells to LDH-A suppression. LDH-A knockdown by RNA interference (RNAi) induced cancer cell death in p53 wild-type, mutant and p53-null human cancer cell lines, indicating that endogenous LDH-A promotes cancer cell survival irrespective of cancer cell p53 status. Unexpectedly, however, we uncovered a novel role for p53 in the regulation of cancer cell NAD(+) and its reduced form NADH. Thus, LDH-A silencing by RNAi, or its inhibition using a small-molecule inhibitor, resulted in a p53-dependent increase in the cancer cell ratio of NADH:NAD(+). This effect was specific for p53(+/+) cancer cells and correlated with (i) reduced activity of NAD(+)-dependent deacetylase sirtuin 1 (SIRT1) and (ii) an increase in acetylated p53, a known target of SIRT1 deacetylation activity. In addition, activation of the redox-sensitive anticancer drug EO9 was enhanced selectively in p53(+/+) cancer cells, attributable to increased activity of NAD(P)H-dependent oxidoreductase NQO1 (NAD(P)H quinone oxidoreductase 1). Suppressing LDH-A increased EO9-induced DNA damage in p53(+/+) cancer cells, but importantly had no additive effect in non-cancer cells. Our results identify a unique strategy by which the NADH/NAD(+) cellular redox status can be modulated in a cancer-specific, p53-dependent manner and we show that this can impact upon the activity of important NAD(H)-dependent enzymes. To summarise, this work indicates two distinct mechanisms by which suppressing LDH-A could potentially be used to kill cancer cells selectively, (i) through induction of apoptosis, irrespective of cancer cell p53 status and (ii) as a part of a combinatorial approach with redox-sensitive anticancer drugs via a novel p53/NAD(H)-dependent mechanism.