Lactate Is a Natural Suppressor of RLR Signaling by Targeting MAVS.

RLR-mediated type I IFN production plays a pivotal role in elevating host immunity for viral clearance and cancer immune surveillance. Here, we report that glycolysis, which is inactivated during RLR activation, serves as a barrier to impede type I IFN production upon RLR activation. RLR-triggered MAVS-RIG-I recognition hijacks hexokinase binding to MAVS, leading to the impairment of hexokinase mitochondria localization and activation. Lactate serves as a key metabolite responsible for glycolysis-mediated RLR signaling inhibition by directly binding to MAVS transmembrane (TM) domain and preventing MAVS aggregation. Notably, lactate restoration reverses increased IFN production caused by lactate deficiency. Using pharmacological and genetic approaches, we show that lactate reduction by lactate dehydrogenase A (LDHA) inactivation heightens type I IFN production to protect mice from viral infection. Our study establishes a critical role of glycolysis-derived lactate in limiting RLR signaling and identifies MAVS as a direct sensor of lactate, which functions to connect energy metabolism and innate immunity.

Glycolytic ATP fuels phosphoinositide 3-kinase signaling to support effector T helper 17 cell responses.

Aerobic glycolysis-the Warburg effect-converts glucose to lactate via the enzyme lactate dehydrogenase A (LDHA) and is a metabolic feature of effector T cells. Cells generate ATP through various mechanisms and Warburg metabolism is comparatively an energy-inefficient glucose catabolism pathway. Here, we examined the effect of ATP generated via aerobic glycolysis in antigen-driven T cell responses. Cd4CreLdhafl/fl mice were resistant to Th17-cell-mediated experimental autoimmune encephalomyelitis and exhibited defective T cell activation, migration, proliferation, and differentiation. LDHA deficiency crippled cellular redox balance and inhibited ATP production, diminishing PI3K-dependent activation of Akt kinase and thereby phosphorylation-mediated inhibition of Foxo1, a transcriptional repressor of T cell activation programs. Th17-cell-specific expression of an Akt-insensitive Foxo1 recapitulated the defects seen in Cd4CreLdhafl/fl mice. Induction of LDHA required PI3K signaling and LDHA deficiency impaired PI3K-catalyzed PIP3 generation. Thus, Warburg metabolism augments glycolytic ATP production, fueling a PI3K-centered positive feedback regulatory circuit that drives effector T cell responses.

NBS1 lactylation is required for efficient DNA repair and chemotherapy resistance.

The Warburg effect is a hallmark of cancer that refers to the preference of cancer cells to metabolize glucose anaerobically rather than aerobically1,2. This results in substantial accumulation of lacate, the end product of anaerobic glycolysis, in cancer cells3. However, how cancer metabolism affects chemotherapy response and DNA repair in general remains incompletely understood. Here we report that lactate-driven lactylation of NBS1 promotes homologous recombination (HR)-mediated DNA repair. Lactylation of NBS1 at lysine 388 (K388) is essential for MRE11-RAD50-NBS1 (MRN) complex formation and the accumulation of HR repair proteins at the sites of DNA double-strand breaks. Furthermore, we identify TIP60 as the NBS1 lysine lactyltransferase and the 'writer' of NBS1 K388 lactylation, and HDAC3 as the NBS1 de-lactylase. High levels of NBS1 K388 lactylation predict poor patient outcome of neoadjuvant chemotherapy, and lactate reduction using either genetic depletion of lactate dehydrogenase A (LDHA) or stiripentol, a lactate dehydrogenase A inhibitor used clinically for anti-epileptic treatment, inhibited NBS1 K388 lactylation, decreased DNA repair efficacy and overcame resistance to chemotherapy. In summary, our work identifies NBS1 lactylation as a critical mechanism for genome stability that contributes to chemotherapy resistance and identifies inhibition of lactate production as a promising therapeutic cancer strategy.

The long noncoding RNA glycoLINC assembles a lower glycolytic metabolon to promote glycolysis.

Non-covalent complexes of glycolytic enzymes, called metabolons, were postulated in the 1970s, but the concept has been controversial. Here we show that a c-Myc-responsive long noncoding RNA (lncRNA) that we call glycoLINC (gLINC) acts as a backbone for metabolon formation between all four glycolytic payoff phase enzymes (PGK1, PGAM1, ENO1, and PKM2) along with lactate dehydrogenase A (LDHA). The gLINC metabolon enhances glycolytic flux, increases ATP production, and enables cell survival under serine deprivation. Furthermore, gLINC overexpression in cancer cells promotes xenograft growth in mice fed a diet deprived of serine, suggesting that cancer cells employ gLINC during metabolic reprogramming. We propose that gLINC makes a functional contribution to cancer cell adaptation and provide the first example of a lncRNA-facilitated metabolon.

Cell-state-specific metabolic dependency in hematopoiesis and leukemogenesis.

The balance between oxidative and nonoxidative glucose metabolism is essential for a number of pathophysiological processes. By deleting enzymes that affect aerobic glycolysis with different potencies, we examine how modulating glucose metabolism specifically affects hematopoietic and leukemic cell populations. We find that a deficiency in the M2 pyruvate kinase isoform (PKM2) reduces the levels of metabolic intermediates important for biosynthesis and impairs progenitor function without perturbing hematopoietic stem cells (HSCs), whereas lactate dehydrogenase A (LDHA) deletion significantly inhibits the function of both HSCs and progenitors during hematopoiesis. In contrast, leukemia initiation by transforming alleles putatively affecting either HSCs or progenitors is inhibited in the absence of either PKM2 or LDHA, indicating that the cell-state-specific responses to metabolic manipulation in hematopoiesis do not apply to the setting of leukemia. This finding suggests that fine-tuning the level of glycolysis may be explored therapeutically for treating leukemia while preserving HSC function.

Microbiota-Derived Lactate Activates Production of Reactive Oxygen Species by the Intestinal NADPH Oxidase Nox and Shortens Drosophila Lifespan.

Commensal microbes colonize the gut epithelia of virtually all animals and provide several benefits to their hosts. Changes in commensal populations can lead to dysbiosis, which is associated with numerous pathologies and decreased lifespan. Peptidoglycan recognition proteins (PGRPs) are important regulators of the commensal microbiota and intestinal homeostasis. Here, we found that a null mutation in Drosophila PGRP-SD was associated with overgrowth of Lactobacillus plantarum in the fly gut and a shortened lifespan. L. plantarum-derived lactic acid triggered the activation of the intestinal NADPH oxidase Nox and the generation of reactive oxygen species (ROS). In turn, ROS production promoted intestinal damage, increased proliferation of intestinal stem cells, and dysplasia. Nox-mediated ROS production required lactate oxidation by the host intestinal lactate dehydrogenase, revealing a host-commensal metabolic crosstalk that is probably broadly conserved. Our findings outline a mechanism whereby host immune dysfunction leads to commensal dysbiosis that in turn promotes age-related pathologies.

KCNK1 promotes proliferation and metastasis of breast cancer cells by activating lactate dehydrogenase A (LDHA) and up-regulating H3K18 lactylation.

Breast cancer is the most prevalent malignancy and the most significant contributor to mortality in female oncology patients. Potassium Two Pore Domain Channel Subfamily K Member 1 (KCNK1) is differentially expressed in a variety of tumors, but the mechanism of its function in breast cancer is unknown. In this study, we found for the first time that KCNK1 was significantly up-regulated in human breast cancer and was correlated with poor prognosis in breast cancer patients. KCNK1 promoted breast cancer proliferation, invasion, and metastasis in vitro and vivo. Further studies unexpectedly revealed that KCNK1 increased the glycolysis and lactate production in breast cancer cells by binding to and activating lactate dehydrogenase A (LDHA), which promoted histones lysine lactylation to induce the expression of a series of downstream genes and LDHA itself. Notably, increased expression of LDHA served as a vicious positive feedback to reduce tumor cell stiffness and adhesion, which eventually resulted in the proliferation, invasion, and metastasis of breast cancer. In conclusion, our results suggest that KCNK1 may serve as a potential breast cancer biomarker, and deeper insight into the cancer-promoting mechanism of KCNK1 may uncover a novel therapeutic target for breast cancer treatment.

eIF4EHP promotes Ldh mRNA translation in and fruit fly adaptation to hypoxia.

Hypoxia induces profound modifications in the gene expression program of eukaryotic cells due to lowered ATP supply resulting from the blockade of oxidative phosphorylation. One significant consequence of oxygen deprivation is the massive repression of protein synthesis, leaving a limited set of mRNAs to be translated. Drosophila melanogaster is strongly resistant to oxygen fluctuations; however, the mechanisms allowing specific mRNA to be translated into hypoxia are still unknown. Here, we show that Ldh mRNA encoding lactate dehydrogenase is highly translated into hypoxia by a mechanism involving a CA-rich motif present in its 3' untranslated region. Furthermore, we identified the cap-binding protein eIF4EHP as a main factor involved in 3'UTR-dependent translation under hypoxia. In accordance with this observation, we show that eIF4EHP is necessary for Drosophila development under low oxygen concentrations and contributes to Drosophila mobility after hypoxic challenge. Altogether, our data bring new insight into mechanisms contributing to LDH production and Drosophila adaptation to oxygen variations.

H3K18 lactylation accelerates liver fibrosis progression through facilitating SOX9 transcription.

Liver fibrosis is a significant health concern globally due to its association with severe liver conditions like cirrhosis and liver cancer. Histone lactylation has been implicated in the progression of hepatic fibrosis, but its specific role in liver fibrosis, particularly regarding H3K18 lactylation, remained unclear. To investigate this, we established in vivo and in vitro models of liver fibrosis using carbon tetrachloride (CCl4) injection in rats and stimulation of hepatic stellate cells (HSCs) with TGF-ß1, respectively. We found that histone lactylation, particularly H3K18 lactylation, was upregulated in both CCl4-induced rats and TGF-ß1-activated HSCs, indicating its potential involvement in liver fibrosis. Further experiments revealed that lactate dehydrogenase A (LDHA) knockdown inhibited H3K18 lactylation and had a beneficial effect on liver fibrosis by suppressing HSC proliferation, migration, and extracellular matrix (ECM) deposition. This suggests that H3K18 lactylation promotes liver fibrosis progression. Chromatin immunoprecipitation (ChIP) and luciferase reporter assays demonstrated that H3K18 lactylation facilitated the transcription of SOX9, a transcription factor associated with fibrosis. Importantly, overexpression of SOX9 counteracted the effects of LDHA silencing on activated HSCs, indicating that SOX9 is downstream of H3K18 lactylation in promoting liver fibrosis. In summary, this study uncovers a novel mechanism by which H3K18 lactylation contributes to liver fibrosis by activating SOX9 transcription. This finding opens avenues for exploring new therapeutic strategies for hepatic fibrosis targeting histone lactylation pathways.

Characteristics of Myocardial Structure and Central Carbon Metabolism during the Early and Compensatory Stages of Cardiac Hypertrophy.

Cardiac hypertrophy is a classical forerunner of heart failure and myocardial structural and metabolic remodeling are closely associated with cardiac hypertrophy. We aim to investigate the characteristics of myocardial structure and central carbon metabolism of cardiac hypertrophy at different stages. Using echocardiography and pathological staining, early and compensatory cardiac hypertrophy were respectively defined as within 7 days and from 7 to 14 days after transverse aortic constriction (TAC) in mice. Among mass-spectrometry-based metabolomics, we identified 45 central carbon metabolites. Differential metabolite analysis showed that six metabolites, including citrate, cis-aconitate and so on, decreased significantly on day 1 after TAC. Ten metabolites, including l-lactate, (S)-2-hydroxyglutarate and so on, were obviously changed on days 10 and 14. Pathway analysis showed that these metabolites were involved in seven metabolic pathways, including carbohydrates, amino acids and so on. Western blot showed the expression of ATP-citrate lyase, malate dehydrogenase 1 and lactate dehydrogenase A in myocardium changed markedly on day 3, while the phosphorylation level of AMP-activated protein kinase did not show significantly difference. We hope our research will promote deeper understanding and early diagnosis of cardiac hypertrophy in clinical practice. All raw data were deposited in MetaboLights (MTBLS10555).

Downregulated expression of lactate dehydrogenase in adult oligodendrocytes and its implication for the transfer of glycolysis products to axons.

Oligodendrocytes and astrocytes are metabolically coupled to neuronal compartments. Pyruvate and lactate can shuttle between glial cells and axons via monocarboxylate transporters. However, lactate can only be synthesized or used in metabolic reactions with the help of lactate dehydrogenase (LDH), a tetramer of LDHA and LDHB subunits in varying compositions. Here we show that mice with a cell type-specific disruption of both Ldha and Ldhb genes in oligodendrocytes lack a pathological phenotype that would be indicative of oligodendroglial dysfunctions or lack of axonal metabolic support. Indeed, when combining immunohistochemical, electron microscopical, and in situ hybridization analyses in adult mice, we found that the vast majority of mature oligodendrocytes lack detectable expression of LDH. Even in neurodegenerative disease models and in mice under metabolic stress LDH was not increased. In contrast, at early development and in the remyelinating brain, LDHA was readily detectable in immature oligodendrocytes. Interestingly, by immunoelectron microscopy LDHA was particularly enriched at gap junctions formed between adjacent astrocytes and at junctions between astrocytes and oligodendrocytes. Our data suggest that oligodendrocytes metabolize lactate during development and remyelination. In contrast, for metabolic support of axons mature oligodendrocytes may export their own glycolysis products as pyruvate rather than lactate. Lacking LDH, these oligodendrocytes can also "funnel" lactate through their "myelinic" channels between gap junction-coupled astrocytes and axons without metabolizing it. We suggest a working model, in which the unequal cellular distribution of LDH in white matter tracts facilitates a rapid and efficient transport of glycolysis products among glial and axonal compartments.

L-Lactate dehydrogenase from Cyanidioschyzon merolae shows high catalytic efficiency for pyruvate reduction and is inhibited by ATP.

L-Lactate is a commodity chemical used in various fields. Microorganisms have produced L-lactate via lactic fermentation using saccharides derived from crops as carbon sources. Recently, L-lactate production using microalgae, whose carbon source is carbon dioxide, has been spotlighted because the prices of the crops have increased. A red alga Cyanidioschyzon merolae produce L-lactate via lactic fermentation under dark anaerobic conditions. The L-lactate titer of C. merolae is higher than those of other microalgae but lower than those of heterotrophic bacteria. Therefore, an increase in the L-lactate titer is required in C. merolae. L-Lactate dehydrogenase (L-LDH) catalyzes the reduction of pyruvate to L-lactate during lactic fermentation. C. merolae possesses five isozymes of L-LDH. The results of previous transcriptome analysis suggested that L-LDHs are the key enzymes in the lactic fermentation of C. merolae. However, their biochemical characteristics, such as catalytic efficiency and tolerance for metabolites, have not been revealed. We compared the amino acid sequences of C. merolae L-LDHs (CmLDHs) and characterized one of the isozymes, CmLDH1. BLAST analysis revealed that the sequence similarities of CmLDH1 and the other isozymes were above 99%. The catalytic efficiency of CmLDH1 under its optimum conditions was higher than those of L-LDHs of other organisms. ATP decreased the affinity and turnover number of CmLDH1 for NADH. These findings contribute to understanding the characteristics of L-LDHs of microalgae and the regulatory mechanisms of lactic fermentation in C. merolae.

Mechanisms of gelofusine protection in an in vitro model of polymyxin B-associated renal injury.

Polymyxins are a last-resort treatment option for multidrug-resistant gram-negative bacterial infections, but they are associated with nephrotoxicity. Gelofusine was previously shown to reduce polymyxin-associated kidney injury in an animal model. However, the mechanism(s) of renal protection has not been fully elucidated. Here, we report the use of a cell culture model to provide insights into the mechanisms of renal protection. Murine epithelial proximal tubular cells were exposed to polymyxin B. Cell viability, lactate dehydrogenase (LDH) release, polymyxin B uptake, mitochondrial superoxide production, nuclear morphology, and apoptosis activation were evaluated with or without concomitant gelofusine. A megalin knockout cell line was used as an uptake inhibition control. Methionine was included in selected experiments as an antioxidant control. A polymyxin B concentration-dependent reduction in cell viability was observed. Increased viability was observed in megalin knockout cells following comparable polymyxin B exposures. Compared with polymyxin B exposure alone, concomitant gelofusine significantly increased cell viability as well as reduced LDH release, polymyxin B uptake, mitochondrial superoxide, and apoptosis. Gelofusine and methionine were more effective at reducing renal cell injury in combination than either agent alone. In conclusion, the mechanisms of renal protection by gelofusine involve decreasing cellular drug uptake, reducing subsequent oxidative stress and apoptosis activation. These findings would be valuable for translational research into clinical strategies to attenuate drug-associated acute kidney injury.NEW & NOTEWORTHY Gelofusine is a gelatinous saline solution with the potential to attenuate polymyxin-associated nephrotoxicity. We demonstrated that the mechanisms of gelofusine renal protection involve reducing polymyxin B uptake by proximal tubule cells, limiting subsequent oxidative stress and apoptosis activation. In addition, gelofusine was more effective at reducing cellular injury than a known antioxidant control, methionine, and a megalin knockout cell line, indicating that gelofusine likely has additional pharmacological properties besides only megalin inhibition.

Deciphering Evolutionary Trajectories of Lactate Dehydrogenases Provides New Insights into Allostery.

Lactate dehydrogenase (LDH, EC.1.1.127) is an important enzyme engaged in the anaerobic metabolism of cells, catalyzing the conversion of pyruvate to lactate and NADH to NAD+. LDH is a relevant enzyme to investigate structure-function relationships. The present work provides the missing link in our understanding of the evolution of LDHs. This allows to explain (i) the various evolutionary origins of LDHs in eukaryotic cells and their further diversification and (ii) subtle phenotypic modifications with respect to their regulation capacity. We identified a group of cyanobacterial LDHs displaying eukaryotic-like LDH sequence features. The biochemical and structural characterization of Cyanobacterium aponinum LDH, taken as representative, unexpectedly revealed that it displays homotropic and heterotropic activation, typical of an allosteric enzyme, whereas it harbors a long N-terminal extension, a structural feature considered responsible for the lack of allosteric capacity in eukaryotic LDHs. Its crystallographic structure was solved in 2 different configurations typical of the R-active and T-inactive states encountered in allosteric LDHs. Structural comparisons coupled with our evolutionary analyses helped to identify 2 amino acid positions that could have had a major role in the attenuation and extinction of the allosteric activation in eukaryotic LDHs rather than the presence of the N-terminal extension. We tested this hypothesis by site-directed mutagenesis. The resulting C. aponinum LDH mutants displayed reduced allosteric capacity mimicking those encountered in plants and human LDHs. This study provides a new evolutionary scenario of LDHs that unifies descriptions of regulatory properties with structural and mutational patterns of these important enzymes.

The four subunits of rabbit skeletal muscle lactate dehydrogenase do not exert their catalytic action additively.

Oligomeric enzymes containing multiple active sites are usually considered to perform their catalytic action at higher rates when compared with their monomeric counterparts. This implies, in turn, that the activity performed by different holoenzyme subunits features additivity. Nevertheless, the extent of this additivity occurring in holoenzymes is far from being adequately understood. To tackle this point, we used tetrameric rabbit lactate dehydrogenase (rbLDH) as a model system to assay the reduction of pyruvate catalysed by this enzyme at the expense of ß-NADH under pre-steady-state conditions. In particular, we observed the kinetics of reactions triggered by concentrations of ß-NADH equimolar to 1, 2, 3, or all 4 subunits of the rbLDH holoenzyme, in the presence of an excess of pyruvate. Surprisingly, when the concentration of the limiting reactant exceeded that of a single holoenzyme subunit, we observed a sharp slowdown of the enzyme conformational rearrangements associated to the generation and the release of l-lactate. Furthermore, using a model to interpret the complex kinetics observed under the highest concentration of the limiting reactant, we estimated the diversity of the rates describing the action of the different rbLDH subunits.

LDHB-deficient brain exhibits resistance to ischemic neuronal cell death due to increased vasodilation.

Ischemic stroke triggers a cascade of metabolic and inflammatory events leading to neuronal death, particularly in the hippocampus. Here, we investigate the role of lactate metabolism in ischemic resistance using LDHB-deficient mice, which exhibit impaired lactate utilization. Contrary to expectations of severe neuronal damage due to metabolic defects, LDHB-deficient mice displayed significantly increased neuronal survival following ischemic insult. Magnetic resonance spectroscopy revealed elevated lactate levels in LDHB-deficient brains, which correlated with enhanced vasodilation of the posterior communicating artery (PComA) and increased extracellular PGE2 levels. These findings suggest that elevated lactate inhibits PGE2 reabsorption, promoting vasodilation and neuronal protection. Our results highlight lactate's potential role in neuroprotection and its therapeutic promise for ischemic stroke.

Structural basis of lactate dehydrogenase A-gossypol complex.

Lactate dehydrogenase A (LDHA) is a key enzyme in Warburg's effect, a characteristic of cancer cells. LDHA is a target of anticancer agents that inhibit the metabolism of cancer cells. Gossypol is a known cancer therapeutic agent that inhibits LDHA by competitive inhibition. However, the mechanisms of inhibition of LDHA by gossypol is unknown. Here, we elucidate the binding of gossypol and LDHA using biochemical and biophysical methods. The crystal structure of the complex between LDHA and gossypol is presented. The binding of gossypol affects LDHA activity by a conformational change in the active-site loop. Our research contributes to the structural insight into LDHA with gossypol and approaches gossypol as a novel therapeutic candidate targeting the metabolic pathways for cancer cells.

Epigenetic silencing of LDHB promotes hepatocellular carcinoma by remodeling the tumor microenvironment.

Lactate dehydrogenase B (LDHB) reversibly catalyzes the conversion of pyruvate to lactate or lactate to pyruvate and expressed in various malignancies. However, the role of LDHB in modulating immune responses against hepatocellular carcinoma (HCC) remains largely unknown. Here, we found that down-regulation of lactate dehydrogenase B (LDHB) was coupled with the promoter hypermethylation and knocking down the DNA methyltransferase 3A (DNMT 3A) restored LDHB expression levels in HCC cell lines. Bioinformatics analysis of the HCC cohort from The Cancer Genome Atlas revealed a significant positive correlation between LDHB expression and immune regulatory signaling pathways and immune cell infiltrations. Moreover, immune checkpoint inhibitors (ICIs) have shown considerable promise for HCC treatment and patients with higher LDHB expression responded better to ICIs. Finally, we found that overexpression of LDHB suppressed HCC growth in immunocompetent but not in immunodeficient mice, suggesting that the host immune system was involved in the LDHB-medicated tumor suppression. Our findings indicate that DNMT3A-mediated epigenetic silencing of LDHB may contribute to HCC progression through remodeling the tumor immune microenvironment, and LDHB may become a potential prognostic biomarker and therapeutic target for HCC immunotherapy.

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.

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

BACKGROUND: The 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. METHODS: In 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. RESULTS: FGF1, 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. CONCLUSION: The FGF pathway facilitates glycolysis by activating LDHA and suppressing LDHB in a STAT1-dependent manner in PCa.