Lactate Dehydrogenase A Research Articles

LncRNA PWRN1 inhibits the progression of hepatocellular carcinoma by activating PKM2 activity

Hepatocellular carcinoma (HCC) is one of the most prevalent and leading causes of cancer-related mortality worldwide. Long non-coding RNAs (lncRNAs) have been demonstrated to play vital roles in cancer development and progression. The lncRNA PWRN1 (PWRN1), acts as a tumor suppressor factor, which is low expressed in some cancers. However, the molecular mechanisms underlying the effects of PWRN1, especially the regulatory relationship with RNA binding protein in HCC remain largely unknown. In the present study, we demonstrated that PWRN1 was significantly down-regulated in HCC and correlated with better prognosis; furthermore, gain-of-function experiments showed that PWRN1 inhibited the proliferation of HCC cells. We further found that PWRN1 up-regulated pyruvate kinase activity and thus hinders the proliferation of HCC in vitro and in vivo. Mechanistically, pyruvate kinase M2 (PKM2) was bound to it and maintained the high activity state of PKM2, thereby hindering PKM2 from entering the nucleus in the form of low-activity dimers, reducing the expression of c-Myc downstream gene LDHA, leading to a decrease in lactate levels, and inhibiting the growth of tumor cells. In addition, PWRN1 was found to inhibit aerobic glycolysis. Finally, TEPP-46, a pyruvate kinase activator, appeared to inhibit HCC proliferation by maintaining tetramer stability and increasing pyruvate kinase activity. Taken together, our results provide new insights into the biology hindering HCC proliferation and indicate that PWRN1 in combination with PKM2 activators might represent a novel therapeutic target for HCC.

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.

Inhibition of glycolysis and SIRT1/GLUT1 signaling ameliorates the apoptotic effect of Leptosidin in prostate cancer cells.

Since the silent information regulation 2 homolog-1 (sirtuin, SIRT1) and glucose transporter 1 (GLUT1) are known to modulate cancer cell metabolism and proliferation, the role of SIRT1/GLUT1 signaling was investigated in the apoptotic effect of Leptosidin from Coreopsis grandiflora in DU145 and PC3 human prostate cancer (PCa) cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell cycle analysis, Western blotting, cBioportal correlation analysis, and co-immunoprecipitation were used in this work. Leptosidin showed cytotoxicity, augmented sub-G1 population, and abrogated the expression of pro-poly (ADP-ribose) polymerase (pro-PARP) and pro-cysteine aspartyl-specific protease (pro-caspase3) in DU145 and PC3 cells. Also, Leptosidin inhibited the expression of SIRT1, GLUT1, pyruvate kinase isozymes M2 (PKM2), Hexokinase 2 (HK2), and lactate dehydrogenase A (LDHA) in DU145 and PC3 cells along with disrupted binding of SIRT1 and GLUT1. Consistently, Leptosidin curtailed lactate, glucose, and ATP in DU145 and PC3 cells. Furthermore, SIRT1 depletion enhanced the decrease of GLUT1, LDHA, and pro-Cas3 by Leptosidin in treated DU145 cells, while pyruvate suppressed the ability of Leptosidin in DU145 cells. These findings suggest that Leptosidin induces apoptosis via inhibition of glycolysis and SIRT1/GLUT1 signaling axis in PCa cells.

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.

Site-specific controlled-release nanoparticles for immune reprogramming via dual metabolic inhibition against triple-negative breast cancer

Metabolic heterogeneity and the tumor immunosuppressive microenvironment (TIME) of triple-negative breast cancer (TNBC) hinder therapeutic effectiveness. Although emerging metabolic therapy and immunotherapy show promise, they are limited by off-target effects and immune escape. Here, a redox-activatable, sequentially-releasing nanoparticle (AMANC@M) for tumor-targeted delivery of anticancer agents and CRISPR/Cas9 has been developed. AMANC@M can reverse the TIME through dual metabolic inhibition, thereby enhancing TNBC therapy. AMANC@M demonstrates excellent biosafety and targets tumors precisely through biomimetic hybrid membrane-mediated homologous homing and the enhanced permeability and retention (EPR) effect. Once internalized into tumor cells, the CRISPR/Cas9 system (“energy nanolock”) is released through glutathione (GSH) cleavage and effectively knocks down the expression of lactate dehydrogenase A (LDHA) to suppress glycolysis. After peeling off of the gene editing shell, a newly synthesized targeted drug, CPI-Z2 (“nutrihijacker” and “energy nanolock”), is released in a controlled manner to block the mitochondrial tricarboxylic acid (TCA) cycle. Nitric oxide (NO) produced from loaded L-arginine enhances the efficiency of CPI-Z2 and reduces drug resistance. Combined with NO therapy, both blockades of nutrients and energy production transform the hypoxia and acidic TIME into an immunocompetent tumor microenvironment (TME) for tumor elimination. Furthermore, AMANC@M offers capabilities for photothermal (PT) therapy and provides clear imaging through PT, photoacoustic (PA), or computed tomography (CT) signals in tumor tissue. Thus, this study provides a new and promising sequentially stimuli-responsive targeting strategy for nanoparticle development, making it a potential treatment candidate for TNBC and other tumors.

Effect and mechanism of Yueju Pills on breast cancer induced by DMBA in rats

This paper aims to explore the inhibitory effect of Yueju Pills on breast cancer and decipher the underlying mechanism. A total of 92 SPF-grade SD female rats were involved in this study, and 14 of them were randomly selected into control group. The remaining 78 rats were administrated with 7,12-dimethylbenzanthracene(DMBA) by gavage to establish the breast cancer model. The modeled rats were randomized into model, tamoxifen(1.9 mg·kg~(-1)·d~(-1)), and low-and high-dose(17, 34 g·kg~(-1)·d~(-1)) Yueju Pills groups. The mental state, food intake, and activities of the rats were observed daily, and the body weight was measured on alternate days. After 12 weeks of administration, the rats were sacrificed and the tumor weight was measured. The serum estrogen and progeste-rone levels were determined by enzyme-linked immunosorbent assay. The histopathological changes of the breast and tumor were observed by hematoxylin-eosin staining. Western blot was employed to measure the protein levels of glucose transporter 1(GLUT1), lactate dehydrogenase A(LDHA), phosphofructokinase muscle(PFKM), pyruvate kinase isozyme type M2(PKM2), hexokinase 2(HK2), nuclear factor-kappaB(NF-κB), and phosphorylated NF-κB. The intestinal microbiome was examined by 16S rRNA high-throughput sequencing. The results showed that compared with the model group, high and low-dose Yueju Pills showed the tumor inhibition rate of 15.8% and 64.5%, respectively, and the low dose group had stronger inhibitory effect. Compared with the control group, the model group presented elevated the levels of estrogen and progesterone in serum. The administration of Yueju Pills lowered such ele-vation, and the low-dose group showed stronger lowering effect(P&lt;0.05). Compared with the model group, Yueju Pills reduced the glands with increased breast tissue, the degree of breast duct expansion, the number and area of acinar cavity, the secretions, and the layers of mammary epithelial cells. Furthermore, Yueju Pills down-regulated the expression of GLUT1, LDHA, PFKM, PKM2, HK2, and NF-κB(P&lt;0.05) and altered the diversity, composition, structure, and abundance of intestinal flora. The results showed that Yueju Pills could inhibit breast cancer by regulating the secretion of estrogen and progesterone, glycolysis, inflammatory cytokines, and intestinal flora.

Salvianolic Acid B Alleviates Liver Injury by Regulating Lactate-Mediated Histone Lactylation in Macrophages.

Salvianolic acid B (Sal B) is the primary water-soluble bioactive constituent derived from the roots of Salvia miltiorrhiza Bunge. This research was designed to reveal the potential mechanism of Sal B anti-liver injury from the perspective of macrophages. In our lipopolysaccharide-induced M1 macrophage model, Sal B showed a clear dose-dependent gradient of inhibition of the macrophage trend of the M1 type. Moreover, Sal B downregulated the expression of lactate dehydrogenase A (LDHA), while the overexpression of LDHA impaired Sal B's effect of inhibiting the trend of macrophage M1 polarization. Additionally, this study revealed that Sal B exhibited inhibitory effects on the lactylation process of histone H3 lysine 18 (H3K18la). In a ChIP-qPCR analysis, Sal B was observed to drive a reduction in H3K18la levels in the promoter region of the LDHA, NLRP3, and IL-1β genes. Furthermore, our in vivo experiments showed that Sal B has a good effect on alleviating CCl4-induced liver injury. An examination of liver tissues and the Kupffer cells isolated from those tissues proved that Sal B affects the M1 polarization of macrophages and the level of histone lactylation. Together, our data reveal that Sal B has a potential mechanism of inhibiting the histone lactylation of macrophages by downregulating the level of LDHA in the treatment of liver injury.

Gene Expression of Glycolysis Enzymes in MCF-7 Breast Cancer Cells Exposed to Warburg Effect and Hypoxia.

Hypoxia can cause significant changes in the glucose metabolism of cancer cells that prefer aerobic glycolysis for energy production instead of the conventional oxidative phosphorylation mechanism. In this study, breast cancer cells (MCF-7) were exposed to glucose (0-5.5-15-55 mM), during specific incubation periods (3, 6, 12, or 24 hours) under normoxic and hypoxic conditions. The expression levels of hypoxia-inducible factor-1α (HIF-1α), glucose transporter-1 (GLUT-1), and glycolytic enzymes at varying glucose concentrations in cells were investigated in the different oxygen environments. It was determined that glycolytic enzymes [Hexokinase 2 (HK2), Pyruvate Kinase M2 (PKM2), Glucose-6-phosphate dehydrogenase (G6PD), Lactate Dehydrogenase A (LDHA), Glyceraldehyde-3-phosphate Dehydrogenase (GAPDH), and Phosphofructokinase M (PFKM)] increased at the transcriptional level, especially in the first hours. This increase indicates that major metabolic reprogramming in response to hypoxia probably occurs over a short period of time. The increase in G6PD gene expression under high glucose and hypoxia conditions suggests that the pentose phosphate pathway (PPP) is used by cancer cells to synthesize necessary precursors for the cell. The results of the study showed that there is a significant interaction between hypoxia and glycolytic metabolism in cancer cells. It is thought that metabolic pathways activated by hypoxia and related genes located in these pathways will contribute to the literature by offering the potential to be target molecules for therapeutic purposes.

Hepatocyte-specific Smad4 deficiency inhibits hepatocarcinogenesis by promoting CXCL10/CXCR3-dependent CD8+- T cell-mediated anti-tumor immunity.

Rationale: Sma mothers against decapentaplegic homologue 4 (Smad4) is a key mediator of the transforming growth factor β (TGF-β) pathway and plays complex and contradictory roles in hepatocellular carcinoma (HCC). However, the specific role of Smad4 in hepatocytes in regulating hepatocarcinogenesis remains poorly elucidated. Methods: A diethylnitrosamine/carbon tetrachloride-induced HCC model was established in mice with hepatocyte-specific Smad4 deletion (AlbSmad4-/-) and liver tumorigenesis was monitored. Immune cell infiltration was examined by immunofluorescence and fluorescence activated cell sorting (FACS). Cytokine secretion, glycolysis, signal pathway, and single-cell RNA sequencing were analysed for mechanism. Results: AlbSmad4-/- mice exhibited significantly fewer and smaller liver tumor nodules, less fibrosis, reduced myeloid-derived suppressor cell infiltration and increased CD8+ T cell infiltration. Smad4 deletion in hepatocytes enhanced C-X-C motif ligand 10 (CXCL10) secretion, promoting tumor necrosis factor-α (TNF-α) production in CD8+ T cells. The loss of Smad4 activated the CXCL10/mammalian target of rapamycin (mTOR)/lactate dehydrogenase A (LDHA) pathway, which increased glycolytic activity in CD8+ T cells. HCC patients with high Smad4 expression exhibited decreased CD8+ T cell infiltration and altered glycolysis. Conclusion: Our results demonstrate that Smad4 in hepatocytes promotes hepatocarcinogenesis and is a potential and candidate target for the prevention and therapy of HCC.

Hypoxia-inducible factor-1α promotes macrophage functional activities in protecting hypoxia-tolerant large yellow croaker (Larimichthys crocea) against Aeromonas hydrophila infection.

The immune system requires a high energy expenditure to resist pathogen invasion. Macrophages undergo metabolic reprogramming to meet these energy requirements and immunologic activity and polarize to M1-type macrophages. Understanding the metabolic pathway switching in large yellow croaker (Larimichthys crocea) macrophages in response to lipopolysaccharide (LPS) stimulation and whether this switching affects immunity is helpful in explaining the stronger immunity of hypoxia-tolerant L. crocea. In this study, transcript levels of glycolytic pathway genes (Glut1 and Pdk1), mRNA levels or enzyme activities of glycolytic enzymes [hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK), and lactate dehydrogenase A (LDHA)], aerobic respiratory enzymes [pyruvate dehydrogenase (PDH), isocitrate dehydrogenase (IDH), and succinate dehydrogenase (SDH)], metabolites [lactic acid (LA) and adenosine triphosphate (ATP)], levels of bactericidal products [reactive oxygen species (ROS) and nitric oxide (NO)], and transcripts and level changes of inflammatory factors [IL1β, TNFα, and interferon (IFN) γ] were detected in LPS-stimulated L. crocea head kidney macrophages. We showed that glycolysis was significantly induced, the tricarboxylic acid (TCA) cycle was inhibited, and metabolic reprogramming occurred, showing the Warburg effect when immune cells were activated. To determine the potential regulatory mechanism behind these changes, LcHIF-1α was detected and found to be significantly induced and transferred to the nucleus after LPS stimulation. LcHif-1α interference led to a significant reduction in glycolytic pathway gene transcript expression, enzyme activity, metabolites, bactericidal substances, and inflammatory factor levels; a significant increase in the aerobic respiration enzymes; and decreased migration, invasion, and phagocytosis. Further ultrastructural observation by electron microscopy showed that fewer microspheres contained phagocytes and that more cells were damaged after LcHif-1α interference. LcHif-1α overexpression L. crocea head kidney macrophages showed the opposite trend, and promoter activities of Ldha and Il1β were significantly enhanced after LcHif-1α overexpression in HEK293T cells. Our data showed that LcHIF-1α acted as a metabolic switch in L. crocea macrophages and was important in polarization. Hypoxia-tolerant L. crocea head kidney showed a stronger Warburg effect and inhibited the TCA cycle, higher metabolites, and bactericidal substance levels. These results collectively revealed that LcHif-1α may promote the functional activities of head kidney macrophages in protecting hypoxia-tolerant L. crocea from Aeromonas hydrophila infection.

Single-cell sequencing of the retina shows that LDHA regulates pathogenesis of autoimmune uveitis

Autoimmune uveitis (AU) is a severe disorder causing poor vision and blindness. However, the cellular dynamics and pathogenic mechanisms underlying retinal injury in uveitis remain unclear. In this study, single-cell RNA sequencing of the retina and cervical draining lymph nodes in experimental autoimmune uveitis mice was conducted to identify the cellular spatiotemporal dynamics and upregulation of the glycolysis-related gene LDHA. Suppression of LDHA can rescue the imbalance of T effector (Teff) cells/T regulator (Treg) cells under inflammation via downregulation of the glycolysis-PI3K signaling circuit and inhibition of the migration of CXCR4+ Teff cells towards retinal tissue. Furthermore, LDHA and CXCR4 are upregulated in the peripheral blood mononuclear cells of Vogt-Koyanagi-Harada patients. The LDHA inhibitor suppresses CD4+ T cell proliferation in humans. Therefore, our data indicate that the autoimmune environment of uveitis regulates Teff cell accumulation in the retina via glycolysis-associated LDHA. Modulation of this target may provide a novel therapeutic strategy for treating AU.

SFXN1 as a potential diagnostic and prognostic biomarker of LUAD is associated with 18F-FDG metabolic parameters

BackgroundSideroflexin 1 (SFXN1) has been discovered as a novel tumor marker for lung adenocarcinoma, but data on its importance in the development of lung adenocarcinoma is still limited. This study evaluated the correlation between SFXN1 and parameters related to 18F-flurodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT), and further explored the role of SFXN1 in the value-added and glycolytic processes of LUAD. MethodThe expression and prognostic value of SFXN1 mRNA in LUAD were analyzed using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) data base. Retrospective analysis of 18F-FDG PET imaging and metabolic parameters in 42 patients to explore the relationship between the expression of SFXN1 and glucose metabolism levels in lung adenocarcinoma and its clinical significance. H1975 cells were selected as the in vitro research object, and the biological effects of SFXN1 on LUAD were further elucidated through Edu proliferation assay, CCK8 activity assay, wound healing experiment, and cell flow cytometry. ResultSFXN1 is highly expressed in various tumors, including LUAD, and its high expression can serve as an independent predictor of overall survival in lung adenocarcinoma. In addition, the expression of SFXN1 in LUAD was significantly correlated with 18F-FDG PET/CT parameters: maximum and average standardized uptake values (SUVmax and SUVmean), as well as total lesion glycolysis (TLG) (rho = 0.574, 0.589, and 0.338, p < 0.05), which can predict the expression of SFXN1 with an accuracy of 0.934. In vitro functional experiments have shown that knocking down SFXN1 inhibits the proliferation and migration of LUAD cells, promotes cell apoptosis, and may inhibit tumor activity by regulating the expression of glycolytic related genes SLC2A1, HK2, GPI, ALDOA, GAPDH, ENO1, PKM, and LDHA. ConclusionThe overexpression of SFXN1 is closely related to FDG uptake, and SFXN1, as a promising prognostic biomarker, may mediate the development of LUAD through the glycolytic pathway.

KIF20B and MET, hub genes of DIAPHs, predict poor prognosis and promote pancreatic cancer progression

BackgroundThe DIAPHs (DIAPH1, DIAPH2, and DIAPH3) are members of the diaphanous subfamily of the formin family. KIF20B and MET, hub genes of DIAPHs, play crucial roles in cytoskeletal remodeling, cell migration, and adhesion. However, their combined prognostic and treatment value in pancreatic adenocarcinoma (PC) warrants further investigation. MethodsMultiomics analysis tools were used to comprehensively assess the genomic expression and prognostic value of KIF20B and MET in PC. Immune cell infiltration, functional enrichment, single-cell RNA-seq (scRNA) analysis, potential therapeutic drugs, and nomograms were established and analyzed. CCK-8 levels, transwell assay, Co-IP assay, mass spectrometry, and western blotting were performed to assess the role of KIF20B and MET as modulators of β-catenin and Lactate Dehydrogenase A (LDHA) in vitro. Xenograft tumor models were used to evaluate the anti-tumor effects in vivo. ResultsDIAPHs, KIF20B, and MET were overexpressed and functioned as poor prognostic markers of PC. Immunoinfiltration analysis revealed that pDC and NK cells were enriched with low expression levels of KIF20B and MET, whereas Th2 cells were enriched with high expression levels of these two genes. The copy number variations (CNVs) in KIF20B and MET were positively correlated with B cell and CD4 + T cell infiltration. Immunological checkpoints NT5E and CD44 were positively correlated with KIF20B and MET expression. Moreover, the nomogram constructed based on KIF20B and MET demonstrated predictive value for overall survival. scRNA-Seq analysis indicated that KIF20B and MET were enriched in endothelial, malignant, B, T, and CD8 + T cells, which correlated with glycolysis and the epithelial-mesenchymal transition (EMT). The interactions of KIF20B and MET with β-catenin and LDHA were verified by Co-IP assay and mass spectrometry. Knockdown of KIF20B and MET downregulates β-catenin and LDHA in vitro. Furthermore, dual knockdown of KIF20B and MET exhibited a synergistic suppressive effect on PC progression in vitro and in vivo. ConclusionDIAPHs, KIF20B, and MET are promising candidates for the prognosis and treatment of PC. More importantly, downregulation of KIF20B and MET inhibited pancreatic cancer progression by regulating LDHA and EMT.

Artificial Protein Crosstalk with a Molecule that Exchanges Binding Partners.

Drawing inspiration from allosteric signaling enzymes, whose catalytic and regulatory units are non-covalently linked, we have devised a method to establish unnatural, effector-mediated enzyme activation within native cells. The feasibility of this approach is demonstrated by introducing a synthetic regulatory unit (sRU) onto glycogen synthase kinase 3 (GSK-3) through non-covalent means. Our study reveals that this synthetic regulator mediates an unnatural crosstalk between GSK-3 and lactate dehydrogenase A (LDHA), whose expression is regulated by cellular oxygen levels. Specifically, with this approach, the constitutively active GSK-3 is transformed into an activable enzyme, whereas LDHA is repurposed as an unnatural effector protein that controls the activity of the kinase, making it unnaturally dependent on the cell's hypoxic response. These findings demonstrate a step toward imitating the function of effector-regulated cell-signaling enzymes, which play a key biological role in mediating the response of cells to changes in their environment. In addition, at the proof-of-principle level, our results indicate the potential to develop a new class of protein inhibitors whose inhibitory effect in cells is dictated by the cell's environment and consequent protein expression profile.

Artificial Protein Crosstalk with a Molecule that Exchanges Binding Partners

AbstractDrawing inspiration from allosteric signaling enzymes, whose catalytic and regulatory units are non‐covalently linked, we have devised a method to establish unnatural, effector‐mediated enzyme activation within native cells. The feasibility of this approach is demonstrated by introducing a synthetic regulatory unit (sRU) onto glycogen synthase kinase 3 (GSK‐3) through non‐covalent means. Our study reveals that this synthetic regulator mediates an unnatural crosstalk between GSK‐3 and lactate dehydrogenase A (LDHA), whose expression is regulated by cellular oxygen levels. Specifically, with this approach, the constitutively active GSK‐3 is transformed into an activable enzyme, whereas LDHA is repurposed as an unnatural effector protein that controls the activity of the kinase, making it unnaturally dependent on the cell‘s hypoxic response. These findings demonstrate a step toward imitating the function of effector‐regulated cell‐signaling enzymes, which play a key biological role in mediating the response of cells to changes in their environment. In addition, at the proof‐of‐principle level, our results indicate the potential to develop a new class of protein inhibitors whose inhibitory effect in cells is dictated by the cell‘s environment and consequent protein expression profile.

Lactate-induced histone lactylation by p300 promotes osteoblast differentiation.

Lactate, which is synthesized as an end product by lactate dehydrogenase A (LDHA) from pyruvate during anaerobic glycolysis, has attracted attention for its energy metabolism and oxidant effects. A novel histone modification-mediated gene regulation mechanism termed lactylation by lactate was recently discovered. The present study examined the involvement of histone lactylation in undifferentiated cells that underwent differentiation into osteoblasts. C2C12 cells cultured in medium with a high glucose content (4500 mg/L) showed increases in marker genes (Runx2, Sp7, Tnap) indicating BMP-2-induced osteoblast differentiation and ALP staining activity, as well as histone lactylation as compared to those cultured in medium with a low glucose content (900 mg/L). Furthermore, C2C12 cells stimulated with the LDH inhibitor oxamate had reduced levels of BMP-2-induced osteoblast differentiation and histone lactylation, while addition of lactate to C2C12 cells cultured in low glucose medium resulted in partial restoration of osteoblast differentiation and histone lactylation. These results indicate that lactate synthesized by LDHA during glucose metabolism is important for osteoblast differentiation of C2C12 cells induced by BMP-2. Additionally, silencing of p300, a possible modifier of histone lactylation, also inhibited osteoblast differentiation and reduced histone lactylation. Together, these findings suggest a role of histone lactylation in promotion of undifferentiated cells to undergo differentiation into osteoblasts.

Formaldehyde aggravates airway inflammation through induction of glycolysis in an experimental model of asthma exacerbated by lipopolysaccharide

Formaldehyde (FA) exposure has been reported to induce or aggravate allergic asthma. Infection is also a potential risk factor for the onset and aggravation of asthma. However, no study has addressed the effects of FA exposure on asthmatic patients with respiratory infection. FA is ubiquitous in environment and respiratory infections are common in clinics. Therefore, it is necessary to explore whether FA exposure leads to the further worsening of symptoms in asthma patients with existing respiratory infection. In the present study, ovalbumin (OVA) was used to establish the murine asthma model. Lipopolysaccharide (LPS) was intratracheal administrated to mimic asthma with respiratory infection. The mice were exposed to 0.5 mg/m3 FA. FA exposure did not induce a significant aggravation on OVA induced allergic asthma. However, the lung function of specific airway resistance (sRaw), histological changes and cytokines production were greatly aggravated by FA exposure in OVA/LPS induced murine asthma model. Monocyte-derived macrophages (MDMs) were isolated from asthmatic patients. Exposure of MDMs to FA and LPS resulted in increased TNF-α, IL-6, IL-1β, and nitric oxide (NO) production. Lactate produciton and lactate dehydrogenase A (LDHA) expression were found to be upregulated by FA in OVA/LPS induced asthmatic mice and LPS stimulated MDMs. Furthermore, glycolysis inhibitor 2-Deoxy-d-glucose attenuated FA and LPS induced TNF-α, IL-6, IL-1β, and NO production. We conclude that FA exposure can lead to the aggravation of allergic asthma with infection through induction of glycolysis. This study could offer some new insight into how FA promotes asthma development.

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.

The mitochondrial NADH shuttle system is a targetable vulnerability for Group 3 medulloblastoma in a hypoxic microenvironment

Medulloblastoma is a cancerous brain tumor that affects mostly children. Among the four groups defined by molecular characteristics, Group 3, the least well characterized, is also the least favorable, with a survival rate of 50%. Current treatments, based on surgery, radiotherapy, and chemotherapy, are not adequate and the lack of understanding of the different molecular features of Group 3 tumor cells makes the development of effective therapies challenging. In this study, the problem of medulloblastoma is approached from a metabolic standpoint in a low oxygen microenvironment. We establish that Group 3 cells use both the mitochondrial glycerol-3 phosphate (G3PS) and malate-aspartate shuttles (MAS) to produce NADH. Small molecules that target G3PS and MAS show a greater ability to decrease cell proliferation and induce apoptosis specifically of Group 3 cells. In addition, as Group 3 cells show improved respiration in hypoxia, the use of Phenformin, a mitochondrial complex 1 inhibitor, alone or in combination, induced significant cell death. Furthermore, inhibition of the cytosolic NAD+ recycling enzyme lactate dehydrogenase A (LDHA), enhanced the effects of the NADH shuttle inhibitors. In a 3D model using Group 3 human cerebellar organoids, tumor cells also underwent apoptosis upon treatment with NADH shuttle inhibitors. Our study demonstrates metabolic heterogeneity depending on oxygen concentrations and provides potential therapeutic solutions for patients in Group 3 whose tumors are the most aggressive.

Identifying the critical oncogenic mechanism of LDHA based on a prognostic model of T-cell synthetic drivers

BackgroundDespite its early success, immunotherapy focused on removing T-cell inhibition does not achieve the desired effect in most patients. New strategies that target antigen-driven T-cell activation are needed to improve immunotherapy outcomes. However, a comprehensive analysis of synthetic drivers of T-cells is greatly lacking in lung adenocarcinoma (LUAD) and other types of tumors. MethodsWe comprehensively evaluated the patterns of LUAD patients based on T -cell synthetic drivers by unsupervised clustering analysis. A risk model was constructed using Lasso Cox regression analysis. The predicted survival and immunotherapy efficacy of the model was validated by independent cohorts. Finally, single-cell sequencing analysis, and a series of in vitro experiments were conducted to explore the role of lactate dehydrogenase A (LDHA) in the malignant progression of LUAD. ResultsPatients in the high-risk group were characterized by survival disadvantage, a “cold” immune phenotype, and by not having benefitted from immunotherapy. LDHA was shown to promote LUAD cell proliferation, cell cycle, invasion, and migration. Secondly, we found that LDHA induced NF-κB pathway activation, tyrosine kinase inhibitor resistance and immunosuppressant microenvironment. Finally, LDHA was found to be highly expressed in fibroblasts, which may be involved in promoting TKI resistance and mediating the immune escape. ConclusionThis study revealed that the T-cell synthetic driver-associated prognostic model developed herein significantly predicted prognosis and immunotherapy efficacy in LUAD. We further investigated the role of LDHA in the malignant phenotype of tumor cells and tumor microenvironment remodeling, providing a promising and novel therapeutic strategy for LUAD.