Lactate Dehydrogenase A Knockdown Research Articles

Lactate dehydrogenase A (LDHA)-mediated lactate generation promotes pulmonary vascular remodeling in pulmonary hypertension

BackgroundHigh levels of lactate are positively associated with prognosis and mortality in pulmonary hypertension (PH). Lactate dehydrogenase A (LDHA) is a key enzyme for the production of lactate. This study is undertaken to investigate the role and molecular mechanisms of lactate and LDHA in PH.MethodsLactate levels were measured by a lactate assay kit. LDHA expression and localization were detected by western blot and Immunofluorescence. Proliferation and migration were determined by CCK8, western blot, EdU assay and scratch-wound assay. The right heart catheterization and right heart ultrasound were measured to evaluate cardiopulmonary function.ResultsIn vitro, we found that lactate promoted proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) in an LDHA-dependent manner. In vivo, we found that LDHA knockdown reduced lactate overaccumulation in the lungs of mice exposed to hypoxia. Furthermore, LDHA knockdown ameliorated hypoxia-induced vascular remodeling and right ventricular dysfunction. In addition, the activation of Akt signaling by hypoxia was suppressed by LDHA knockdown both in vivo and in vitro. The overexpression of Akt reversed the inhibitory effect of LDHA knockdown on proliferation in PASMCs under hypoxia. Finally, LDHA inhibitor attenuated vascular remodeling and right ventricular dysfunction in Sugen/hypoxia mouse PH model, Monocrotaline (MCT)-induced rat PH model and chronic hypoxia-induced mouse PH model.ConclusionsThus, LDHA-mediated lactate production promotes pulmonary vascular remodeling in PH by activating Akt signaling pathway, suggesting the potential role of LDHA in regulating the metabolic reprogramming and vascular remodeling in PH.

Histone lactylation regulates autophagy of hyperplastic scar fibroblasts by inhibiting the transcriptional activity of phosphatase and tensin homologue.

Hyperplastic scar (HS) is an overreaction of tissue to skin injury caused by local fibroblast proliferation and excessive collagen production. Histone posttranslational modification patterns are important epigenetic processes that control various biological activities. This study was designed to investigate the effects of histone lactylation on HS and the underlying mechanism. Western blot was used to analyse the lactylation level in HS patients and fibroblasts (HSFs). In vitro experiments, western blot, cell counting kit-8, and immunofluorescence staining were performed to detect the collagen level, cell viability, and autophagy, respectively. The relationship between snai2 (SLUG) and phosphatase and tensin homologue (PTEN) was assessed by RNA immunoprecipitation and dual-luciferase reporter assays. The results showed that the histone lactylation level was upregulated in HS tissues and HSFs. HSFs showed increased collagen production and cell viability, and decreased autophagy. Silencing of lactate dehydrogenase A (LDHA) promoted the transcription of PTEN by inhibiting SLUG, thus promoting autophagy. Knockdown of LDHA inhibited collagen deposition and cell viability, and increased autophagy in HSFs, and the results were reversed after PTEN inhibition. In summary, histone lactylation inhibited the transcription activity of PTEN by promoting SLUG, thereby suppressing autophagy and promoting collagen deposition and cell viability of HSFs, which might provide effective therapeutic strategies in HS.

Positive feedback regulation between glycolysis and histone lactylation drives oncogenesis in pancreatic ductal adenocarcinoma

BackgroundMetabolic reprogramming and epigenetic alterations contribute to the aggressiveness of pancreatic ductal adenocarcinoma (PDAC). Lactate-dependent histone modification is a new type of histone mark, which links glycolysis metabolite to the epigenetic process of lactylation. However, the role of histone lactylation in PDAC remains unclear.MethodsThe level of histone lactylation in PDAC was identified by western blot and immunohistochemistry, and its relationship with the overall survival was evaluated using a Kaplan-Meier survival plot. The participation of histone lactylation in the growth and progression of PDAC was confirmed through inhibition of histone lactylation by glycolysis inhibitors or lactate dehydrogenase A (LDHA) knockdown both in vitro and in vivo. The potential writers and erasers of histone lactylation in PDAC were identified by western blot and functional experiments. The potential target genes of H3K18 lactylation (H3K18la) were screened by CUT&Tag and RNA-seq analyses. The candidate target genes TTK protein kinase (TTK) and BUB1 mitotic checkpoint serine/threonine kinase B (BUB1B) were validated through ChIP-qPCR, RT-qPCR and western blot analyses. Next, the effects of these two genes in PDAC were confirmed by knockdown or overexpression. The interaction between TTK and LDHA was identified by Co-IP assay.ResultsHistone lactylation, especially H3K18la level was elevated in PDAC, and the high level of H3K18la was associated with poor prognosis. The suppression of glycolytic activity by different kinds of inhibitors or LDHA knockdown contributed to the anti-tumor effects of PDAC in vitro and in vivo. E1A binding protein p300 (P300) and histone deacetylase 2 were the potential writer and eraser of histone lactylation in PDAC cells, respectively. H3K18la was enriched at the promoters and activated the transcription of mitotic checkpoint regulators TTK and BUB1B. Interestingly, TTK and BUB1B could elevate the expression of P300 which in turn increased glycolysis. Moreover, TTK phosphorylated LDHA at tyrosine 239 (Y239) and activated LDHA, and subsequently upregulated lactate and H3K18la levels.ConclusionsThe glycolysis-H3K18la-TTK/BUB1B positive feedback loop exacerbates dysfunction in PDAC. These findings delivered a new exploration and significant inter-relationship between lactate metabolic reprogramming and epigenetic regulation, which might pave the way toward novel lactylation treatment strategies in PDAC therapy.

A systematic pan-cancer analysis identifies LDHA as a novel predictor for immunological, prognostic, and immunotherapy resistance.

Lactate dehydrogenase A (LDHA), a critical enzyme involved in glycolysis, is broadly involved multiple biological functions in human cancers. It is reported that LDHA can impact tumor immune surveillance and induce the transformation of tumor-associated macrophages, highlighting its unnoticed function of LDHA in immune system. However, in human cancers, the role of LDHA in prognosis and immunotherapy hasn't been investigated. In this study, we analyzed the expression pattern and prognostic value of LDHA in pan-cancer and explored its association between tumor microenvironment (TME), immune infiltration subtype, stemness scores, tumor mutation burden (TMB), and immunotherapy resistance. We found that LDHA expression is tumor heterogeneous and that its high expression is associated with poor prognosis in multiple human cancers. In addition, LDHA expression was positively correlated with the presence of mononuclear/macrophage cells, and also promoted the infiltration of a range of immune cells. Genomic alteration of LDHA was common in different types of cancer, while with prognostic value in pan-cancers. Pan-cancer analysis revealed that the significant correlations existed between LDHA expression and tumor microenvironment (including stromal cells and immune cells) as well as stemness scores (DNAss and RNAss) across cancer types. Drug sensitivity analysis also revealed that LDHA was able to predict response to chemotherapy and immunotherapy. Furthermore, it was confirmed that knockdown of LDHA reduced proliferation and migration ability of lung cancer cells. Taken together, LDHA could serve as a prognostic biomarker and a potential immunotherapy marker.

Lactate dehydrogenase A is implicated in the pathogenesis of B-cell lymphoma through regulation of the FER signaling pathway.

Lactate dehydrogenase A (LDHA) is highly expressed in various tumors. However, the role of LDHA in the pathogenesis of B-cell lymphoma remains unclear. Analysis of data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases revealed an elevated LDHA expression in diffuse large B-cell lymphoma (DLBC) tissues compared with normal tissues. Similarly, our results demonstrated a significant increase in LDHA expression in tumor tissues from the patients with B-cell lymphoma compared with those with lymphadenitis. To further elucidate potential roles of LDHA in B-cell lymphoma pathogenesis, we silenced LDHA in the Raji cells (a B-cell lymphoma cell line) using shRNA techniques. Silencing LDHA led to reduced mitochondrial membrane integrity, adenosine triphosphate (ATP) production, glycolytic activity, cell viability and invasion. Notably, LDHA knockdown substantially suppressed in vivo growth of Raji cells and extended survival in mice bearing lymphoma (Raji cells). Moreover, proteomic analysis identified feline sarcoma-related protein (FER) as a differential protein positively associated with LDHA expression. Treatment with E260, a FER inhibitor, significantly reduced the metabolism, proliferation and invasion of Raji cells. In summary, our findings highlight that LDHA plays multiple roles in B-cell lymphoma pathogenesis via FER pathways, establishing LDHA/FER may as a potential therapeutic target.

The opposite role of lactate dehydrogenase a (LDHA) in cervical cancer under energy stress conditions

Due to insufficient and defective vascularization, the tumor microenvironment is often nutrient-depleted. LDHA has been demonstrated to play a tumor-promoting role by facilitating the glycolytic process. However, whether and how LDHA regulates cell survival in the nutrient-deficient tumor microenvironment is still unclear. Here, we sought to investigate the role and mechanism of LDHA in regulating cell survival and proliferation under energy stress conditions. Our results showed that the aerobic glycolysis levels, cell survival and proliferation of cervical cancer cells decreased significantly after inhibition of LDHA under normal culture condition while LDHA deficiency greatly inhibited glucose starvation-induced ferroptosis and promoted cell proliferation and tumor formation under energy stress conditions. Mechanistic studies suggested that glucose metabolism shifted from aerobic glycolysis to mitochondrial OXPHOS under energy stress conditions and LDHA knockdown increased accumulation of pyruvate in the cytosol, which entered the mitochondria and upregulated the level of oxaloacetate by phosphoenolpyruvate carboxylase (PC). Importantly, the increase in oxaloacetate production after absence of LDHA remarkably activated AMP-activated protein kinase (AMPK), which increased mitochondrial biogenesis and mitophagy, promoted mitochondrial homeostasis, thereby decreasing ROS level. Moreover, repression of lipogenesis by activation of AMPK led to elevated levels of reduced nicotinamide adenine dinucleotide phosphate (NADPH), which effectively resisted ROS-induced cell ferroptosis and enhanced cell survival under energy stress conditions. These results suggested that LDHA played an opposing role in survival and proliferation of cervical cancer cells under energy stress conditions, and inhibition of LDHA may not be a suitable treatment strategy for cervical cancer.

Lactate dehydrogenase A promotes nasopharyngeal carcinoma progression through the TAK1/NF-κB Axis.

Nasopharyngeal carcinoma (NPC) is a malignant tumor that originates in the nasopharyngeal mucosa and is common in China and Southeast Asian countries. Cancer cells reprogram glycolytic metabolism to promote their growth, survival and metastasis. Glycolysis plays an important role in NPC development, but the underlying mechanisms remain incompletely elucidated. Lactate dehydrogenase A (LDHA) is a crucial glycolytic enzyme, catalyzing the last step of glycolysis. This study aims to investigate the exact role of LDHA, which catalyzes the conversion of pyruvate into lactate, in NPC development. The western blot and immunohistochemical (IHC) results indicated that LDHA was significantly upregulated in NPC cells and clinical samples. LDHA knockdown by shRNA significantly inhibited NPC cell proliferation and invasion. Further knockdown of LDHA dramatically weakened the tumorigenicity of NPC cells in vivo. Mechanistic studies showed that LDHA activated TGF-β-activated kinase 1 (TAK1) and subsequent nuclear factor κB (NF-κB) signaling to promote NPC cell proliferation and invasion. Exogenous lactate supplementation restored NPC cell proliferation and invasion inhibited by LDHA knockdown, and this restorative effect was reversed by NF-κB inhibitor (BAY 11-7082) or TAK1 inhibitor (5Z-7-oxozeaenol) treatment. Moreover, clinical sample analyses showed that LDHA expression was positively correlated with TAK1 Thr187 phosphorylation and poor prognosis. Our results suggest that LDHA and its major metabolite lactate drive NPC progression by regulating TAK1 and its downstream NF-κB signaling, which could become a therapeutic target in NPC.

Lactate inhibits interferon-α response in ovarian cancer by inducing STAT1 ubiquitin degradation

The emergence of lactate, produced by lactate dehydrogenase A (LDHA), as an important regulator of the immune response in tumor development has garnered attention in recent research. But, many questions still need to be clarified regarding the relationship between lactate and anti-tumor immunity. Here, we reported that both exogenous and endogenous lactate reduced the protein level and activation of the signal transducer and activator of transcription 1(STAT1) in ovarian cancer cells. As a consequence, the expression of IFNα-STAT1 regulated genes was weakened. This, in turn, weakened the antitumor effect of IFNα by impeding NKT and CD8+T cells recruitment. Strikingly, we found that LDHA knockdown did not result in the downregulation of STAT1 mRNA level in ovarian cancer cells. Instead, we observed that lactate triggered the degradation of STAT1 through the proteasomal pathway. Notably, we identified that lactate reduced the stability of STAT1 by promoting the expression of F-box only protein 40 (Fbxo40). This protein interacts with STAT1 and potentially acts as an E3 ubiquitin ligase, leading to the induction of STAT1 polyubiquitination and degradation. Importantly, ectopic over-expression of the Fbxo40 gene significantly inhibited the expression of ISGs in LDHA knockdown cells. In the TCGA tumor data, we observed that high expression of Fbxo40 negatively correlates with overall survival in ovarian cancer patients. Collectively, our findings reveal lactate as a negative regulator of the IFNα-STAT1 signaling axis in ovarian cancer. This discovery suggests that strategies aimed at targeting lactate for ovarian cancer prevention and treatment should consider the impact on the IFNα-STAT1 response.

Canonical Wnt signaling promotes HSC glycolysis and liver fibrosis through an LDH-A/HIF-1α transcriptional complex.

Aerobic glycolysis reprogramming occurs during HSC activation, but how it is initiated and sustained remains unknown. We investigated the mechanisms by which canonical Wnt signaling regulated HSC glycolysis and the therapeutic implication for liver fibrosis. Glycolysis was examined in HSC-LX2 cells upon manipulation of Wnt/β-catenin signaling. Nuclear translocation of lactate dehydrogenase A (LDH-A) and its interaction with hypoxia-inducible factor-1α (HIF-1α) were investigated using molecular simulation and site-directed mutation assays. The pharmacological relevance of molecular discoveries was intensified in primary cultures, rodent models, and human samples. HSC glycolysis was enhanced by Wnt3a but reduced by β-catenin inhibitor or small interfering RNA (siRNA). Wnt3a-induced rapid transactivation and high expression of LDH-A dependent on TCF4. Wnt/β-catenin signaling also stimulated LDH-A nuclear translocation through importin β2 interplay with a noncanonical nuclear location signal of LDH-A. Mechanically, LDH-A bound to HIF-1α and enhanced its stability by obstructing hydroxylation-mediated proteasome degradation, leading to increased transactivation of glycolytic genes. The Gly28 residue of LDH-A was identified to be responsible for the formation of the LDH-A/HIF-1α transcription complex and stabilization of HIF-1α. Furthermore, LDH-A-mediated glycolysis was required for HSC activation in the presence of Wnt3a. Results in vivo showed that HSC activation and liver fibrosis were alleviated by HSC-specific knockdown of LDH-A in mice. β-catenin inhibitor XAV-939 mitigated HSC activation and liver fibrosis, which were abrogated by HSC-specific LDH-A overexpression in mice with fibrosis. Inhibition of HSC glycolysis by targeting Wnt/β-catenin signaling and LDH-A had therapeutic promise for liver fibrosis.

Lactate dehydrogenase A mediated histone lactylation induced the pyroptosis through targeting HMGB1.

Cerebral ischemia (CI), as the cerebrovascular disease with the highest incidence rate, is treated by limited intravenous thrombolysis and intravascular therapy to recanalize the embolized vessels. Recently, the discovery of histone lactylation proposes a potential molecular mechanism for the role of lactate in physiological and pathological processes. This study aimed to analyze the lactate dehydrogenase A (LDHA) mediated histone lactylation in CI reperfusion (CI/R) injury. Oxygen-glucose deprivation/reoxygenation (OGD/R) treated N2a cells and middle cerebral artery occlusion (MCAO) treated rats was used as the CI/R model in vivo and in vitro. Cell viability and pyroptosis was assessed using CCK-8 and flow cytometry. RT-qPCR was performed to detect the relative expression. The relationship between histone lactylation and HMGB1 was verified by CHIP assay. LDHA, HMGB1, lactate and histone lactylation was up-regulated in the OGD/R treated N2a cells. Additionally, LDHA knockdown decreased HMGB1 levels in vitro, and relieved CI/R injury in vivo. Besides, LDHA silencing declined the histone lactylation mark enrichment on HMGB1 promoter, and lactate supplement rescued it. What?s more, LDHA knockdown decreased the IL-18 and IL-1β contents, and the cleaved-caspase-1 and GSDMD-N protein levels in the OGD/R treated N2a cells, which was reversed by HMGB1 overexpression. Knockdown of LDHA suppressed the pyroptosis in the N2a cells induced by OGD/R, which was reversed by HMGB1 overexpression. Mechanistically, LDHA mediated the histone lactylation induced pyroptosis through targeting HMGB1 in the CI/R injury.

Astrocytic lactate dehydrogenase A regulates neuronal excitability and depressive-like behaviors through lactate homeostasis in mice

Alterations in energy metabolism are associated with depression. However, the role of glycolysis in the pathogenesis of depression and the underlying molecular mechanisms remain unexplored. Through an unbiased proteomic screen coupled with biochemical verifications, we show that the levels of glycolysis and lactate dehydrogenase A (LDHA), a glycolytic enzyme that catalyzes L-lactate production, are reduced in the dorsomedial prefrontal cortex (dmPFC) of stress-susceptible mice in chronic social defeat stress (CSDS) model. Conditional knockout of LDHA from the brain promotes depressive-like behaviors in both male and female mice, accompanied with reduced L-lactate levels and decreased neuronal excitability in the dmPFC. Moreover, these phenotypes could be duplicated by knockdown of LDHA in the dmPFC or specifically in astrocytes. In contrast, overexpression of LDHA reverses these phenotypic changes in CSDS-susceptible mice. Mechanistic studies demonstrate that L-lactate promotes neuronal excitability through monocarboxylic acid transporter 2 (MCT2) and by inhibiting large-conductance Ca2+-activated potassium (BK) channel. Together, these results reveal a role of LDHA in maintaining neuronal excitability to prevent depressive-like behaviors.

LDHA deficiency inhibits trophoblast proliferation via the PI3K/AKT/FOXO1/CyclinD1 signaling pathway in unexplained recurrent spontaneous abortion.

Dysregulated trophoblast proliferation, invasion, and apoptosis may cause several pregnancy-associated complications, such as unexplained recurrent spontaneous abortion (URSA). Recent studies have shown that metabolic abnormalities, including glycolysis inhibition, may dysregulate trophoblast function, leading to URSA. However, the underlying mechanisms remain unclear. Herein, we found that lactate dehydrogenase A (LDHA), a key enzyme in glycolysis, was significantly reduced in the placental villus of URSA patients. The human trophoblast cell line HTR-8/SVneo was used to investigate the possible LDHA-mediated regulation of trophoblast function. LDHA knockdown in HTR-8/SVneo cells induced G0/G1 phase arrest and increased apoptosis, whereas LDHA overexpression reversed these effects. Next, RNA sequencing combined with Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that the PI3K/AKT signaling pathway is potentially affected by downstream genes of LDHA. Especially, we found that LDHA knockdown decreased the phosphorylation levels of PI3K, AKT, and FOXO1, resulting in a significant downregulation of CyclinD1. In addition, treatment with an AKT inhibitor or FOXO1 inhibitor also verified that the PI3K/AKT/FOXO1 signaling pathway influenced the gene expression of CyclinD1 in trophoblast. Moreover, p-AKT expression correlated positively with LDHA expression in syncytiotrophoblasts and extravillous trophoblasts in first-trimester villus. Collectively, this study revealed a new regulatory pathway for LDHA/PI3K/AKT/FOXO1/CyclinD1 in the trophoblast cell cycle and proliferation.

LDHA promotes osteoblast differentiation through histone lactylation

Osteoblast cells tend to metabolize glucose to lactate via aerobic glycolysis during osteogenic differentiation. However, the function of lactate in this process is still elusive. As a newly discovered protein posttranslational modification, lactate-derived histone lactylation has been found to play important roles in gene regulation and have profound effects on diverse biological processes. Here, we found that the expression of lactate dehydrogenase A (LDHA), intracellular lactate, and histone lactylation levels were all gradually increased during osteogenic differentiation. Knockdown of LDHA impaired the formation of mineralized nodules and ALP activity. RNA-sequencing and subsequent validation experiments showed that JunB expression was decreased in LDHA knockdown cells. Mechanistically, knockdown of LDHA decreased histone lactylation mark enrichment on JunB promoter, and exogenous lactate treatment rescued this effect. Our study revealed a non-canonical function of lactate during osteogenic differentiation.

LncRNA NEAT1-associated aerobic glycolysis blunts tumor immunosurveillance by T cells in prostate cancer.

Long noncoding RNA (lncRNA) nuclear enriched abundant transcript 1 (NEAT1) is nuclear-located and transcribed from chromatin 11. To date, little is known about the cellular functions and regulatory mechanisms of NEAT1 in prostate cancer (PCa). In this study, whole-genome RNA sequencing data were downloaded from TCGA and GEO databases. Biological information was used to analyze the different expressions of NEAT1. In situ hybridization (ISH) was performed to detect the expression of NEAT1 in PCa and paracarcinoma clinical samples. Then, NEAT1 was knocked down in PC3 cells through lentiviral infection with a plasmid construct. Bioinformatics and integrative analytical approaches were utilized to identify the relationships of NEAT1 with specific cancer-related gene sets. Cell proliferation assay and colony formation assay were performed to evaluate the cell proliferative ability. Glycolysis stress test, metabolism assay, and infiltrating T-cell function analysis were implemented to assess the changes in metabolism and immune microenvironment of PCa. We found that the expression of NEAT1 was higher in PCa than in non-neoplastic tissues. The cell proliferative capability of PCa cells was significantly reduced in the NEAT1 knockdown group. PCR array and bioinformatics analysis revealed that the enrichment of acidic substance-related gene sets was associated with NEAT1 expression. NEAT1 depletion inhibited PCa cell aerobic glycolysis accompanied by the reduction of lactate levels in the medium. Further, we found that lactate dehydrogenase A (LDHA) expression was positively regulated by NEAT1. At last, co-culture systems indicated that NEAT1 or LDHA knockdown promoted the secretion of CD8+ T-lymphocyte factors, including TNF-α, IFN-γ, and Granzyme B, and enhanced the antitumor effects.

LDHA mediated degradation of extracellular matrix is a potential target for the treatment of aortic dissection

Aortic dissection (AD) is a disease with high mortality and lacks effective drug treatment. Recent studies have shown that the development of AD is closely related to glucose metabolism. Lactate dehydrogenase A (LDHA) is a key glycolytic enzyme and plays an important role in cardiovascular disease. However, the role of LDHA in the progression of AD remains to be elucidated. Here, we found that the level of LDHA was significantly elevated in AD patients and the mouse model established by BAPN combined with Ang II. In vitro, the knockdown of LDHA reduced the growth of human aortic vascular smooth muscle cells (HAVSMCs), glucose consumption, and lactate production induced by PDGF-BB. The overexpression of LDHA in HAVSMCs promoted the transformation of HAVSMCs from contractile phenotype to synthetic phenotype, and increased the expression of MMP2/9. Mechanistically, LDHA promoted MMP2/9 expression through the LDHA-NDRG3-ERK1/2-MMP2/9 pathway. In vivo, Oxamate, LDH and lactate inhibitor, reduced the degradation of elastic fibers and collagen deposition, inhibited the phenotypic transformation of HAVSMCs from contractile phenotype to synthetic phenotype, reduced the expression of NDRG3, p-ERK1/2, and MMP2/9, and delayed the progression of AD. To sum up, the increase of LDHA promotes the production of MMP2/9, stimulates the degradation of extracellular matrix (ECM), and promoted the transformation of HAVSMCs from contractile phenotype to synthetic phenotype. Oxamate reduced the progression of AD in mice. LDHA may be a therapeutic target for AD.

The Warburg effect as a therapeutic target for bladder cancers and intratumoral heterogeneity in associated molecular targets.

Bladder cancer is the 10th most common cancer worldwide. For muscle‐invasive bladder cancer (MIBC), treatment includes radical cystectomy, radiotherapy, and chemotherapy; however, the outcome is generally poor. For non–muscle‐invasive bladder cancer (NMIBC), tumor recurrence is common. There is an urgent need for more effective and less harmful therapeutic approaches. Here, bladder cancer cell metabolic reprogramming to rely on aerobic glycolysis (the Warburg effect) and expression of associated molecular therapeutic targets by bladder cancer cells of different stages and grades, and in freshly resected clinical tissue, is investigated. Importantly, analyses indicate that the Warburg effect is a feature of both NMIBCs and MIBCs. In two in vitro inducible epithelial‐mesenchymal transition (EMT) bladder cancer models, EMT stimulation correlated with increased lactate production, the end product of aerobic glycolysis. Protein levels of lactate dehydrogenase A (LDH‐A), which promotes pyruvate enzymatic reduction to lactate, were higher in most bladder cancer cell lines (compared with LDH‐B, which catalyzes the reverse reaction), but the levels did not closely correlate with aerobic glycolysis rates. Although LDH‐A is expressed in normal urothelial cells, LDH‐A knockdown by RNAi selectively induced urothelial cancer cell apoptotic death, whereas normal cells were unaffected—identifying LDH‐A as a cancer‐selective therapeutic target for bladder cancers. LDH‐A and other potential therapeutic targets (MCT4 and GLUT1) were expressed in patient clinical specimens; however, positive staining varied in different areas of sections and with distance from a blood vessel. This intratumoral heterogeneity has important therapeutic implications and indicates the possibility of tumor cell metabolic coupling.

Functional inhibition of lactate dehydrogenase suppresses pancreatic adenocarcinoma progression.

BackgroundPancreatic adenocarcinoma (PAAD) a highly lethal malignancy. The current use of clinical parameters may not accurately predict the clinical outcome, which further renders the unsatisfactory therapeutic outcome.MethodsIn this study, we retrospectively analyzed the clinical‐pathological characteristics and prognosis of 253 PAAD patients. Univariate, multivariate, and Kaplan‐Meier survival analyses were conducted to assess risk factors and clinical outcomes. For functional study, we performed bidirectional genetic manipulation of lactate dehydrogenase A (LDHA) in PAAD cell lines to measure PAAD progression by both in vitro and in vivo assays.ResultsLDHA is particularly overexpressed in PAAD tissues and elevated serum LDHA‐transcribed isoenzymes‐5 (LDH‐5) was associated with poorer patients’ clinical outcomes. Genetic overexpression of LDHA promoted the proliferation and invasion in vitro, and tumor growth and metastasis in vivo in murine PAAD orthotopic models, while knockdown of LDHA exhibited opposite effects. LDHA‐induced L‐lactate production was responsible for the LDHA‐facilitated PAAD progression. Mechanistically, LDHA overexpression reduced the phosphorylation of metabolic regulator AMPK and promoted the downstream mTOR phosphorylation in PAAD cells. Inhibition of mTOR repressed the LDHA‐induced proliferation and invasion. A natural product berberine was selected as functional inhibitor of LDHA, which reduced activity and expression of the protein in PAAD cells. Berberine inhibited PAAD cells proliferation and invasion in vitro, and suppressed tumor progression in vivo. The restoration of LDHA attenuated the suppressive effect of berberine on PAAD.ConclusionsOur findings suggest that LDHA may be a novel biomarker and potential therapeutic target of human PAAD.

LDHA induces EMT gene transcription and regulates autophagy to promote the metastasis and tumorigenesis of papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is one of the most common kinds of endocrine-related cancer and has a heterogeneous prognosis. Metabolic reprogramming is one of the hallmarks of cancers. Aberrant glucose metabolism is associated with malignant biological behavior. However, the functions and mechanisms of glucose metabolism genes in PTC are not fully understood. Thus, data from The Cancer Genome Atlas database were analyzed, and lactate dehydrogenase A (LDHA) was determined to be a potential novel diagnostic and therapeutic target for PTCs. The research objective was to investigate the expression of LDHA in PTCs and to explore the main functions and relative mechanisms of LDHA in PTCs. Higher expression levels of LDHA were found in PTC tissues than in normal thyroid tissues at both the mRNA and protein levels. Higher expression levels of LDHA were correlated with aggressive clinicopathological features and poor prognosis. Moreover, we found that LDHA not only promoted PTC migration and invasion but also enhanced tumor growth both in vitro and in vivo. In addition, we revealed that the metabolic products of LDHA catalyzed induced the epithelial–mesenchymal transition process by increasing the relative gene H3K27 acetylation. Moreover, LDHA knockdown activated the AMPK pathway and induced protective autophagy. An autophagy inhibitor significantly enhanced the antitumor effect of FX11. These results suggested that LDHA enhanced the cell metastasis and proliferation of PTCs and may therefore become a potential therapeutic target for PTCs.

POU1F1 transcription factor induces metabolic reprogramming and breast cancer progression via LDHA regulation

Metabolic reprogramming is considered hallmarks of cancer. Aerobic glycolysis in tumors cells has been well-known for almost a century, but specific factors that regulate lactate generation and the effects of lactate in both cancer cells and stroma are not yet well understood. In the present study using breast cancer cell lines, human primary cultures of breast tumors, and immune deficient murine models, we demonstrate that the POU1F1 transcription factor is functionally and clinically related to both metabolic reprogramming in breast cancer cells and fibroblasts activation. Mechanistically, we demonstrate that POU1F1 transcriptionally regulates the lactate dehydrogenase A (LDHA) gene. LDHA catalyzes pyruvate into lactate instead of leading into the tricarboxylic acid cycle. Lactate increases breast cancer cell proliferation, migration, and invasion. In addition, it activates normal-associated fibroblasts (NAFs) into cancer-associated fibroblasts (CAFs). Conversely, LDHA knockdown in breast cancer cells that overexpress POU1F1 decreases tumor volume and [18F]FDG uptake in tumor xenografts of mice. Clinically, POU1F1 and LDHA expression correlate with relapse- and metastasis-free survival. Our data indicate that POU1F1 induces a metabolic reprogramming through LDHA regulation in human breast tumor cells, modifying the phenotype of both cancer cells and fibroblasts to promote cancer progression.

Lactate Dehydrogenase A Governs Cardiac Hypertrophic Growth in Response to Hemodynamic Stress

SUMMARYThe heart manifests hypertrophic growth in response to high blood pressure, which may decompensate and progress to heart failure under persistent stress. Metabolic remodeling is an early event in this process. However, its role remains to be fully characterized. Here, we show that lactate dehydrogenase A (LDHA), a critical glycolytic enzyme, is elevated in the heart in response to hemodynamic stress. Cardiomyocyte-restricted deletion of LDHA leads to defective cardiac hypertrophic growth and heart failure by pressure overload. Silencing of LDHA in cultured cardiomyocytes suppresses cell growth from pro-hypertrophic stimulation in vitro, while overexpression of LDHA is sufficient to drive cardiomyocyte growth. Furthermore, we find that lactate is capable of rescuing the growth defect from LDHA knockdown. Mechanistically, lactate stabilizes NDRG3 (N-myc downregulated gene family 3) and stimulates ERK (extracellular signal-regulated kinase). Our results together suggest that the LDHA/NDRG3 axis may play a critical role in adaptive cardiomyocyte growth in response to hemodynamic stress.