Lactate Dehydrogenase A Expression Research Articles

HOXC4 promotes proliferation of pancreatic cancer cells by increasing LDHA-mediated glycolysis.

Homeobox C4 (HOXC4) is a member of homeobox family and acts as a transcription factor in regulating morphological development. The current study aimed to determine its role in pancreatic cancer (PC). Bioinformatics analysis was employed to assess the expression and clinical significance of HOXC4 in PC, while the expression of HOXC4 was further confirmed in PC tissues through quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC). The impact of HOXC4 on PC cell proliferation was evaluated using various assays including Cell Counting Kit-8, colony formation, apoptosis detection, cell cycle analysis, and subcutaneous tumorigenesis. Extracellular acidification rate, glucose uptake, and lactate production measurements were detected to examine the impact of HOXC4 on glycolysis. The relationship between HOXC4 and lactate dehydrogenase A (LDHA) was investigated using CHIP assay, luciferase reporter assay, and western blot. Notably, there was a substantial increase in HOXC4 expression in PC, and patients with elevated HOXC4 levels exhibited shorter survival durations. HOXC4 knockdown resulted in significantly reduced proliferation and colony formation in PC cells, accompanied by increased apoptosis and G1 phase arrest. The overexpression of HOXC4 resulted in contrasting effects. In vivo, the proliferation of PC cells was diminished upon the knockdown of HOXC4. HOXC4 exhibited an increase in LDHA expression by binding to its promoter. The suppressive effects of HOXC4 knockdown on PC cells were counteracted upon the restoration of LDHA. In conclusion, HOXC4 promoted the proliferation of PC cells by increasing LDHA-mediated glycolysis. HOXC4 can act as a target for PC therapy.

Intrathecal Fumagillin Alleviates Chronic Neuropathy-Induced Nociceptive Sensitization and Modulates Spinal Astrocyte-Neuronal Glycolytic and Angiogenic Proteins.

Nociceptive sensitization is accompanied by the upregulation of glycolysis in the central nervous system in neuropathic pain. Growing evidence has demonstrated glycolysis and angiogenesis to be related to the inflammatory processes. This study investigated whether fumagillin inhibits neuropathic pain by regulating glycolysis and angiogenesis. Fumagillin was administered through an intrathecal catheter implanted in rats with chronic constriction injury (CCI) of the sciatic nerve. Nociceptive, behavioral, and immunohistochemical analyses were performed to evaluate the effects of the inhibition of spinal glycolysis-related enzymes and angiogenic factors on CCI-induced neuropathic pain. Fumagillin reduced CCI-induced thermal hyperalgesia and mechanical allodynia from postoperative days (POD) 7 to 14. The expression of angiogenic factors, vascular endothelial growth factor (VEGF) and angiopoietin 2 (ANG2), increased in the ipsilateral lumbar spinal cord dorsal horn (SCDH) following CCI. The glycolysis-related enzymes, pyruvate kinase M2 (PKM2) and lactate dehydrogenase A (LDHA) significantly increased in the ipsilateral lumbar SCDH following CCI on POD 7 and 14 compared to those in the control rats. Double immunofluorescence staining indicated that VEGF and PKM2 were predominantly expressed in the astrocytes, whereas ANG2 and LDHA were predominantly expressed in the neurons. Intrathecal infusion of fumagillin significantly reduced the expression of angiogenic factors and glycolytic enzymes upregulated by CCI. The expression of hypoxia-inducible factor-1α (HIF-1α), a crucial transcription factor that regulates angiogenesis and glycolysis, was also upregulated after CCI and inhibited by fumagillin. We concluded that intrathecal fumagillin may reduce the expression of ANG2 and LDHA in neurons and VEGF and PKM2 in the astrocytes of the SCDH, further attenuating spinal angiogenesis in neuropathy-induced nociceptive sensitization. Hence, fumagillin may play a role in the inhibition of peripheral neuropathy-induced neuropathic pain by modulating glycolysis and angiogenesis.

Unraveling the role of LDHA and VEGFA in oxidative stress: A pathway to therapeutic interventions in cerebral aneurysms.

Cerebral aneurysms (CA) are critical conditions often associated with oxidative stress in vascular endothelial cells (VECs). The enzyme lactate dehydrogenase A (LDHA) plays a crucial role in glycolysis and lactate metabolism, processes implicated in the pathogenesis of aneurysms. Understanding these molecular mechanisms can inform the development of novel therapeutic targets. This study investigated the role of lactate metabolism and lactate-related genes, particularly LDHA and vascular endothelial growth factor A (VEGFA) genes, in VECs during oxidative stress. Using the GSE26969 dataset, we identified differential expression of lactate-related genes and performed functional enrichment analysis, revealing significant associations with glycolysis and lactate metabolic pathways. To induce oxidative stress, VECs were treated with H2O2, and the expression of LDHA and VEGFA was analyzed using quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting (WB) assays. Under oxygen-glucose deprivation/reperfusion (OGD/R) conditions, the effects of LDHA overexpression and VEGFA knockdown on cell viability and apoptosis were evaluated. Immunoprecipitation combined with western blotting was used to detect the lactylation status of LDHA following OGD/R stimulation and treatment with lactic acid (LA) and 2-deoxyglucose (2-DG). Our results indicated that oxidative stress modulates LDHA expression, glucose uptake, and lactate production, suggesting a metabolic shift towards glycolysis. LDHA overexpression improved cell survival and reduced apoptosis, while VEGFA knockdown had the opposite effect. Additionally, 2-DG treatment reduced LDHA lactylation and apoptosis. Our findings demonstrated that LDHA plays a critical role in the oxidative stress response of VECs, highlighting the potential therapeutic value of targeting glycolysis in CA. This study contributes to the understanding of metabolic adaptations in vascular pathologies and suggests new avenues for therapeutic intervention in CA management.

LDHA-mediated M2-type macrophage polarization via tumor-derived exosomal EPHA2 promotes renal cell carcinoma progression.

Lactate dehydrogenase A (LDHA) is known to promote the growth and invasion of various types of tumors, affects tumor resistance, and is associated with tumor immune escape. But how LDHA reshapes the tumor microenvironment and promotes the progression of renal cell carcinoma (RCC) remains unclear. In this study, we found that LDHA was highly expressed in clear cell RCC (ccRCC), and this high expression was associated with macrophage infiltration, while macrophages were highly infiltrated in ccRCC, affecting patient prognosis via M2-type polarization. Our in vivo and in vitro experiments demonstrated that LDHA and M2-type macrophages could enhance the proliferation, invasion, and migration abilities of ccRCC cells. Mechanistically, high expression of LDHA in ccRCC cells upregulated the expression of EPHA2 in exosomes derived from renal cancer. Exosomal EPHA2 promoted M2-type polarization of macrophages by promoting activation of the PI3K/AKT/mTOR pathway in macrophages, thereby promoting the progression of ccRCC. All these findings suggest that EPHA2 may prove to be a potential therapeutic target for advanced RCC.

All-trans-retinoic acid modulates glycolysis via H19 and telomerase: the role of mir-let-7a in estrogen receptor-positive breast cancer cells

BackgroundBreast cancer (BC) is the most commonly diagnosed cancer in women. Treatment approaches that differ between estrogen-positive (ER+) and triple-negative BC cells (TNBCs) and may subsequently affect cancer biomarkers, such as H19 and telomerase, are an emanating delight in BC research. For instance, all-trans-Retinoic acid (ATRA) could represent a potent regulator of these oncogenes, regulating microRNAs, mostly let-7a microRNA (miR-let-7a), which targets the glycolysis pathway, mainly pyruvate kinase M2 (PKM2) and lactate dehydrogenase A (LDHA) enzymes. Here, we investigated the potential role of ATRA in H19, telomerase, miR-let-7a, and glycolytic enzymes modulation in ER + and TNBC cells.MethodsMCF-7 and MDA-MB-231 cells were treated with 5 µM ATRA and/or 100 nM fulvestrant. Then, ATRA-treated or control MCF-7 cells were transfected with either H19 or hTERT siRNA. Afterward, ATRA-treated or untreated MDA-MB-231 cells were transfected with estrogen receptor alpha ER(α) or beta ER(β) expression plasmids. RNA expression was evaluated by RT‒qPCR, and proteins were assessed by Western blot. PKM2 activity was measured using an NADH/LDH coupled enzymatic assay, and telomerase activity was evaluated with a quantitative telomeric repeat amplification protocol assay. Student’s t-test or one-way ANOVA was used to analyze data from replicates.ResultsOur results showed that MCF-7 cells were more responsive to ATRA than MDA-MB-231 cells. In MCF-7 cells, ATRA and/or fulvestrant decreased ER(α), H19, telomerase, PKM2, and LDHA, whereas ER(β) and miR-let-7a increased. H19 or hTERT knockdown with or without ATRA treatment showed similar results to those obtained after ATRA treatment, and a potential interconnection between H19 and hTERT was found. However, in MDA-MB-231 cells, RNA expression of the aforementioned genes was modulated after ATRA and/or fulvestrant, with no significant effect on protein and activity levels. Overexpression of ER(α) or ER(β) in MDA-MB-231 cells induced telomerase activity, PKM2 and LDHA expression, in which ATRA treatment combined with plasmid transfection decreased glycolytic enzyme expression.ConclusionsTo the best of our knowledge, our study is the first to elucidate a new potential interaction between the estrogen receptor and glycolytic enzymes in ER + BC cells through miR-let-7a.

Fibroblast growth factor pathway promotes glycolysis by activating LDHA and suppressing LDHB in a STAT1-dependent manner in prostate cancer

BackgroundThe initiation of fibroblast growth factor 1 (FGF1) expression coincident with the decrease of FGF2 expression is a well-documented event in prostate cancer (PCa) progression. Lactate dehydrogenase A (LDHA) and LDHB are essential metabolic products that promote tumor growth. However, the relationship between FGF1/FGF2 and LDHA/B-mediated glycolysis in PCa progression is not reported. Thus, we aimed to explore whether FGF1/2 could regulate LDHA and LDHB to promote glycolysis and explored the involved signaling pathway in PCa progression.MethodsIn vitro studies used RT‒qPCR, Western blot, CCK-8 assays, and flow cytometry to analyze gene and protein expression, cell viability, apoptosis, and cell cycle in PCa cell lines. Glycolysis was assessed by measuring glucose consumption, lactate production, and extracellular acidification rate (ECAR). For in vivo studies, a xenograft mouse model of PCa was established and treated with an FGF pathway inhibitor, and tumor growth was monitored.ResultsFGF1, FGF2, and LDHA were expressed at high levels in PCa cells, while LDHB expression was low. FGF1/2 positively modulated LDHA and negatively modulated LDHB in PCa cells. The depletion of FGF1, FGF2, or LDHA reduced cell proliferation, induced cell cycle arrest, and inhibited glycolysis. LDHB overexpression showed similar inhibitory effect on PCa cells. Mechanistically, we found that FGF1/2 positively regulated STAT1 and STAT1 transcriptionally activated LDHA expression while suppressed LDHB expression. Furthermore, the treatment of an FGF pathway inhibitor suppressed PCa tumor growth in mice.ConclusionThe FGF pathway facilitates glycolysis by activating LDHA and suppressing LDHB in a STAT1-dependent manner in PCa.

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.

Persistent organic pollutants dysregulate energy homeostasis in human ovaries in vitro

Exposure to persistent organic pollutants (POPs), such as dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs), has historically been linked to population collapses in wildlife. Despite international regulations, these legacy chemicals are still currently detected in women of reproductive age, and their levels correlate with reduced ovarian reserve, longer time-to-pregnancy, and higher risk of infertility. However, the specific modes of action underlying these associations remain unclear. Here, we examined the effects of five commonly occurring POPs − hexachlorobenzene (HCB), p,p'-dichlorodiphenyldichloroethylene (DDE), 2,3,3′,4,4′,5-hexachlorobiphenyl (PCB156), 2,2′,3,4,4′,5,5′-heptachlorobiphenyl (PCB180), perfluorooctane sulfonate (PFOS) − and their mixture on human ovaries in vitro. We exposed human ovarian cancer cell lines COV434, KGN, and PA1 as well as primary ovarian cells for 24 h, and ovarian tissue containing unilaminar follicles for 6 days. RNA-sequencing of samples exposed to concentrations covering epidemiologically relevant levels revealed significant gene expression changes related to central energy metabolism in the exposed cells, indicating glycolysis, oxidative phosphorylation, fatty acid metabolism, and reactive oxygen species as potential shared targets of POP exposures in ovarian cells. Alpha-enolase (ENO1), lactate dehydrogenase A (LDHA), cytochrome C oxidase subunit 4I1 (COX4I1), ATP synthase F1 subunit alpha (ATP5A), and glutathione peroxidase 4 (GPX4) were validated as targets through qPCR in additional cell culture experiments in KGN. In ovarian tissue cultures, we observed significant effects of exposure on follicle growth and atresia as well as protein expression. All POP exposures, except PCB180, decreased unilaminar follicle proportion and increased follicle atresia. Immunostaining confirmed altered expression of LDHA, ATP5A, and GPX4 in the exposed tissues. Moreover, POP exposures modified ATP production in KGN and tissue culture. In conclusion, our results demonstrate the disruption of cellular energy metabolism as a novel mode of action underlying POP-mediated interference of follicle growth in human ovaries.

The Chemokine CXCL7 is Correlated with LDH-A and Predicts the Prognosis of Patients with Colorectal Cancer.

The aims of this study were to evaluate the correlation between chemokine (C-X-C) ligand 7 (CXCL7) expression and glycolysis and to explore the prognostic significance of CXCL7 in colorectal cancer (CRC). The expression of CXCL7 and lactate dehydrogenase A (LDH-A) was measured by immunohistochemistry in tissue from 158 CRC patients. Patients were divided into high expression and low expression groups based on receiver operating characteristic curves and a cut-off value. The correlation between CXCL7 and LDH-A expression was evaluated. The overall survival (OS) times of CRC patients were explored. The risk factors related to prognosis were assessed. Significantly higher expression of CXCL7 and LDH-A was detected in CRC tissue than in non-CRC tissue, and was associated with N stage and tumor-node-metastasis (TNM) stage. CXCL7 expression was strongly correlated with LDH-A expression in CRC tissue. High expression of CXCL7 was validated as an independent risk factor for OS. Increased expression of CXCL7 was positively correlated with LDH-A expression and was an independent risk factor for CRC prognosis.

Circular RNA circTATDN3 promotes the Warburg effect and proliferation in colorectal cancer

As one of the key metabolic enzymes in the glycolytic pathway, lactate dehydrogenase A (LDHA) might be linked to tumor proliferation by driving the Warburg effect. Circular RNAs (circRNAs) are widely implicated in tumor progression. Here, we report that circTATDN3, a circular RNA that interacts with LDHA, plays a critical role in proliferation and energy metabolism in CRC. We found that circTATDN3 expression was increased in CRC cells and tumor tissues and that high circTATDN3 expression was positively associated with poor postoperative prognosis in CRC patients. Additionally, circTATDN3 promoted the proliferation of CRC cells in vivo and vitro. Mechanistically, circTATDN3 was shown to function as an adaptor molecule that enhances the binding of LDHA to FGFR1, leading to increased LDHA phosphorylation and consequently promoting the Warburg effect. Moreover, circTATDN3 increased the expression of LDHA by sponging miR-511-5p, which synergistically promoted CRC progression and the Warburg effect. In conclusion, circTATDN3 may be a target for the treatment of CRC.

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.

Plasma metabolomics reveals risk factors for lung adenocarcinoma.

Metabolic reprogramming plays a significant role in the advancement of lung adenocarcinoma (LUAD), yet the precise metabolic changes remain incompletely understood. This study aims to uncover metabolic indicators associated with the progression of LUAD. A total of 1083 subjects were recruited, including 670 LUAD, 135 benign lung nodules (BLN) and 278 healthy controls (HC). Gas chromatography-mass spectrometry (GC/MS) was used to identify and quantify plasma metabolites. Odds ratios (ORs) were calculated to determine LUAD risk factors, and machine learning algorithms were utilized to differentiate LUAD from BLN. High levels of oxalate, glycolate, glycine, glyceric acid, aminomalonic acid, and creatinine were identified as risk factors for LUAD (adjusted ORs>1.2, P<0.03). Remarkably, oxalate emerged as a distinctive metabolic risk factor exhibiting a strong correlation with the progression of LUAD (adjusted OR=5.107, P<0.001; advanced-stage vs. early-stage). The Random Forest (RF) model demonstrated a high degree of efficacy in distinguishing between LUAD and BLN (accuracy = 1.00 and 0.73, F1-score= 1.00 and 0.79, and AUC = 1.00 and 0.76 in the training and validation sets, respectively). TCGA and GTEx gene expression data have shown that lactate dehydrogenase A (LDHA), a crucial enzyme involved in oxalate metabolism, is increasingly expressed in the progression of LUAD. High LDHA expression levels in LUAD patients are also linked to poor prognoses (HR=1.66, 95% CI=1.34-2.07, P<0.001). This study reveals risk factors associated with LUAD.

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.

Circ_0000376 regulates miR-577/HK2/LDHA signaling pathway to promote the growth, invasion and glycolysis of osteosarcoma

BackgroundMany studies have confirmed that circular RNAs (circRNAs) mediate the malignant progression of various tumors including osteosarcoma (OS). Our study is to uncover novel molecular mechanisms by which circ_0000376 regulates OS progression.MethodsThe expression of circ_0000376, microRNA (miR)-577, hexokinase 2 (HK2) and lactate dehydrogenase-A (LDHA) was determined by quantitative real-time PCR. OS cell proliferation, apoptosis and invasion were measured using cell counting kit 8 assay, colony formation assay, EdU assay, flow cytometry and transwell assay. Besides, cell glycolysis was assessed by testing glucose consumption, lactate production, and ATP/ADP ratios. Protein expression was examined by western blot analysis. The interaction between miR-577 and circ_0000376 or HK2/LADA was verified by dual-luciferase reporter assay. The role of circ_0000376 on OS tumor growth was explored by constructing mice xenograft models.ResultsCirc_0000376 had been found to be upregulated in OS tissues and cells. Functional experiments revealed that circ_0000376 interference hindered OS cell growth, invasion and glycolysis. Circ_0000376 sponged miR-577 to reduce its expression. In rescue experiments, miR-577 inhibitor abolished the regulation of circ_0000376 knockdown on OS cell functions. MiR-577 could target HK2 and LDHA in OS cells. MiR-577 suppressed OS cell growth, invasion and glycolysis, and these effects were reversed by HK2 and LDHA overexpression. Also, HK2 and LDHA expression could be regulated by circ_0000376. In vivo experiments showed that circ_0000376 knockdown inhibited OS tumorigenesis.ConclusionCirc_0000376 contributed to OS growth, invasion and glycolysis depending on the regulation of miR-577/HK2/LDHA axis, providing a potential target for OS treatment.Graphical

Electroacupuncture improves articular microcirculation and attenuates cartilage hypoxia in a male rabbit model of knee osteoarthritis

Background and aimHypoxia of the cartilage has been considered as a potential pathogenic factor in knee osteoarthritis (KOA). Studies have shown that impaired blood perfusion of joint leads to cartilage hypoxia. Electroacupuncture (EA) has proven effects on pain relief and improving microcirculation. This study aimed to explore the effect of EA on articular microcirculation and cartilage anoxic and the underlying mechanisms. ProceduresVideman's method was used for 6 weeks to establish the KOA model. EA intervention was performed in four points around the knee for 3 weeks after KOA modeling. The Lequesne MG score was used to assess ethology. We recorded the oxygen tension of synovial fluid and the synovial microcirculation in vivo. HE-staining was used to assess cartilage morphology, and immunohistochemistry (IHC), Western blotting, and RT-PCR were used to assess expression of the major glycolytic enzymes glucosetransporter1 (GLUT1), pyruvate kinase M2(PKM2), and lactate dehydrogenase A (LDHA). Enzyme-linked immunosorbent assay (Elisa) was used to detect lactate content. Results and conclusionThere was a significant decrease in Lequesne MG score and improvement in Mankin score after EA intervention (P < 0.01), a significant increase in synovial microcirculation (P < 0.05) and synovial fluid oxygen tension (P < 0.01), and there was significant decrease in the expression of GLUT1, PKM2 and LDHA (P < 0.01) and lactate (P < 0.05). This study suggested that EA ameliorate cartilage hypoxia and regulate glycolytic metabolism in chondrocytes in KOA model rabbits by improving articular microcirculation and oxygen tension.

TIMELESS promotes reprogramming of glucose metabolism in oral squamous cell carcinoma

BackgroundOral squamous cell carcinoma (OSCC), the predominant malignancy of the oral cavity, is characterized by high incidence and low survival rates. Emerging evidence suggests a link between circadian rhythm disruptions and cancer development. The circadian gene TIMELESS, known for its specific expression in various tumors, has not been extensively studied in the context of OSCC. This study aims to explore the influence of TIMELESS on OSCC, focusing on cell growth and metabolic alterations.MethodsWe analyzed TIMELESS expression in OSCC using western blot, immunohistochemistry, qRT-PCR, and data from The Cancer Genome Atlas (TCGA) and the Cancer Cell Line Encyclopedia (CCLE). The role of TIMELESS in OSCC was examined through clone formation, MTS, cell cycle, and EdU assays, alongside subcutaneous tumor growth experiments in nude mice. We also assessed the metabolic impact of TIMELESS by measuring glucose uptake, lactate production, oxygen consumption, and medium pH, and investigated its effect on key metabolic proteins including silent information regulator 1 (SIRT1), hexokinase 2 (HK2), pyruvate kinase isozyme type M2 (PKM2), recombinant lactate dehydrogenase A (LDHA) and glucose transporter-1 (GLUT1).ResultsElevated TIMELESS expression in OSCC tissues and cell lines was observed, correlating with reduced patient survival. TIMELESS overexpression enhanced OSCC cell proliferation, increased glycolytic activity (glucose uptake and lactate production), and suppressed oxidative phosphorylation (evidenced by reduced oxygen consumption and altered pH levels). Conversely, TIMELESS knockdown inhibited these cellular and metabolic processes, an effect mirrored by manipulating SIRT1 levels. Additionally, SIRT1 was positively associated with TIMELESS expression. The expression of SIRT1, HK2, PKM2, LDHA and GLUT1 increased with the overexpression of TIMELESS levels and decreased with the knockdown of TIMELESS.ConclusionTIMELESS exacerbates OSCC progression by modulating cellular proliferation and metabolic pathways, specifically by enhancing glycolysis and reducing oxidative phosphorylation, largely mediated through the SIRT1 pathway. This highlights TIMELESS as a potential target for OSCC therapeutic strategies.

Glucose transporter 3 (GLUT3) promotes lactylation modifications by regulating lactate dehydrogenase A (LDHA) in gastric cancer

ObjectivesGlucose transporter 3 (GLUT3) plays a major role in glycolysis and glucose metabolism in cancer cells. We aimed to investigate the correlation between GLUT3 and histone lactylation modification in the occurrence and progression of gastric cancer.Materials and methodsWe initially used single-cell sequencing data to determine the expression levels of GLUT3 and lactate dehydrogenase A (LDHA) in primary tumor, tumor-adjacent normal, and metastasis tumor tissues. Immunohistochemistry analysis was conducted to measure GLUT3, LDHA, and L-lactyl levels in gastric normal and cancer tissues. Transwell and scratch assays were performed to evaluate the metastatic and invasive capacity of gastric cancer cell lines. Western blotting was used to measure L-lactyl and histone lactylation levels in gastric cancer cell lines.ResultsSingle-cell sequencing data showed that GLUT3 expression was significantly increased in primary tumor and metastasis tumor tissues. In addition, GLUT3 expression was positively correlated with that of LDHA expression and lactylation-related pathways. Western blotting and immunohistochemistry analyses revealed that GLUT3 was highly expressed in gastric cancer tissues and cell lines. GLUT3 knockdown in gastric cancer cell lines inhibited their metastatic and invasive capacity to various degrees. Additionally, the levels of LDHA, L-lactyl, H3K9, H3K18, and H3K56 significantly decreased after GLUT3 knockdown, indicating that GLUT3 affects lactylation in gastric cancer cells. Moreover, LDHA overexpression in a GLUT3 knockdown cell line reversed the levels of lactylation and EMT-related markers, and the EMT functional phenotype induced by GLUT3 knockdown. The in vivo results were consistent with the in vitro results.ConclusionsThis study suggests the important role of histone lactylation in the occurrence and progression of gastric cancer, and GLUT3 may be a new diagnostic marker and therapeutic target for gastric cancer.

Abstract 16968: Hypoxia-Lactate Dehydrogenase A-Lactate Axis Mediated Metabolic Adaptation of Macrophage Promotes Vascular Remodeling of Pulmonary Hypertension

Introduction: Early recruitment of inflammatory macrophages with subsequent adaptation into pro-fibrotic phenotype have been reported essential for the development of PH. However, the underlying mechanism remains undetermined. Hypothesis: With enhanced glycolysis under hypoxic conditions, lactate dehydrogenase A(LDHA) mediated accumulation of lactate facilitates metabolic adaptation of macrophages and promotes the development of PH. Methods: Circulating monocytes, lactate, LDHA expression level were analyzed from patients with PH. The expression of LDHA, iNOS, and Arg1 in macrophages within lung tissue were examined on histopathology from patients with IPAH. Mice with myeloid specific knockout of Ldha were generated, and hemodynamic measurement, echocardiogram, histopathological examinations were conducted to evaluate pulmonary vascular remodeling using Su/Hx PH model. Bone marrow derived macrophage (BMDM) and vascular smooth muscle cells (SMCs) from mice were harvested for the mechanism study. Results: Lactate, monocytes and LDHA expression in PBMC were elevated in PH patients. On histopathology, perivascular macrophages infiltration with overexpression of LDHA, iNOS and Arg1 was noticed from lung tissue of IPAH patients, similar seen in both MCT-PH rats and Su/Hx mice. Mice with myeloid knockout of Ldha ( Ldha lyz2-/- ) shown decreased RVSP and improved right heart function on Echocardiogram. In vitro, inflammatory BMDM shown significantly elevated expression of LDHA and lactate under hypoxia, along with oversecreted growth factors including PDGF-β and promoting SMCs proliferation, which can be reversed by Ldha depletion. Conclusions: The hypoxia-LDHA-lactate axis plays a crucial role in metabolic adaption of macrophages under hypoxia condition, promoting SMCs proliferation and pulmonary vascular remodeling process. These findings suggest that targeting LDHA-lactate axis might exert therapeutic potential for PH.

Lactate dehydrogenase A inhibition prevents RANKL-induced osteoclastogenesis by reducing enhanced glycolysis

Osteoclasts are multinucleated, specializes bone-resorbing cells that are derived from the monocyte/macrophage lineage. Excessive resorbing activities of osteoclasts are involved in destructive bone diseases. The detailed mechanism of acidification at the bone adhesion surface during the bone resorption process of osteoclasts remains to be defined. During glycolysis, pyruvate proceeds to the tricarboxylic cycle under aerobic conditions and pyruvate is converted to lactate via lactate dehydrogenase A (LDHA) under anaerobic conditions. However, tumor cells produce ATP during aerobic glycolysis and large amounts of pyruvate are converted to lactate and H+ by LDHA. Lactate and H+ are excreted outside the cell, whereby they are involved in invasion of tumor cells due to the pH drop around the cell. In this study, we focused on aerobic glycolysis and investigated the production of lactate by LDHA in osteoclasts. Expression of LDHA and monocarboxylate transporter 4 (MCT4) was upregulated during osteoclast differentiation. Intracellular and extracellular lactate levels increased with upregulation of LDHA and MCT4, respectively. FX11 (an LDHA inhibitor) inhibited osteoclast differentiation and suppressed the bone-resorbing activity of osteoclasts. We propose that inhibition of LDHA may represent a novel therapeutic strategy for controlling excessive bone resorption in osteoporosis and rheumatoid arthritis.

Persistent hypoxia promotes myofibroblast differentiation via GPR-81 and differential regulation of LDH isoenzymes in normal and idiopathic pulmonary fibrosis fibroblasts.

Hypoxia, a state of insufficient oxygen availability, promotes cellular lactate production. Lactate levels are increased in lungs from patients with idiopathic pulmonary fibrosis (IPF), a disease characterized by excessive scar formation, and lactate is implicated in the pathobiology of lung fibrosis. However, the mechanisms underlying the effects of hypoxia and lactate on fibroblast phenotype are poorly understood. We exposed normal and IPF lung fibroblasts to persistent hypoxia and found that increased lactate generation by IPF fibroblasts was driven by the FoxM1-dependent increase of lactate dehydrogenase A (LDHA) coupled with decreased LDHB that was not observed in normal lung fibroblasts. Importantly, hypoxia reduced α-smooth muscle actin (α-SMA) expression in normal fibroblasts but had no significant impact on this marker of differentiation in IPF fibroblasts. Treatment of control and IPF fibroblasts with TGF-β under hypoxic conditions did not significantly change LDHA or LDHB expression. Surprisingly, lactate directly induced the differentiation of normal, but not IPF fibroblasts under hypoxic conditions. Moreover, while expression of GPR-81, a G-protein-coupled receptor that binds extracellular lactate, was increased by hypoxia in both normal and IPF fibroblasts, its inhibition or silencing only suppressed lactate-mediated differentiation in normal fibroblasts. These studies show that hypoxia differentially affects normal and fibrotic fibroblasts, promoting increased lactate generation by IPF fibroblasts through regulation of the LDHA/LDHB ratio and promoting normal lung fibroblast responsiveness to lactate through GPR-81. This supports a novel paradigm in which lactate may serve as a paracrine intercellular signal in oxygen-deficient microenvironments.