Multi-omics and immunogenomics analysis revealed PFKFB3 as a targetable hallmark and mediates sunitinib resistance in papillary renal cell carcinoma: in silico study with laboratory verification.

Glycolysis-related metabolic reprogramming is a central hallmark of human cancers, especially in renal cell carcinoma. However, the regulatory function of glycolytic signature in papillary RCC has not been well elucidated. In the present study, the glycolysis-immune predictive signature was constructed and validated using WGCNA, glycolysis-immune clustering analysis. PPI network of DEGs was constructed and visualized. Functional enrichments and patients' overall survival were analyzed. QRT-PCR experiments were performed to detect hub genes' expression and distribution, siRNA technology was used to silence targeted genes; cell proliferation and migration assays were applied to evaluate the biological function. Glucose concentration, lactate secretion, and ATP production were measured. Glycolysis-Immune Related Prognostic Index (GIRPI) was constructed and combined analyzed with single-cell RNA-seq. High-GIRPI signature predicted significantly poorer outcomes and relevant clinical features of pRCC patients. Moreover, GIRPI also participated in several pathways, which affected tumor immune microenvironment and provided potential therapeutic strategy. As a key glycolysis regulator, PFKFB3 could promote renal cancer cell proliferation and migration in vitro. Blocking of PFKFB3 by selective inhibitor PFK-015 or glycolytic inhibitor 2-DG significantly restrained renal cancer cells' neoplastic potential. PFK-015 and sunitinib could synergistically inhibit pRCC cells proliferation. Glycolysis-Immune Risk Signature is closely associated with pRCC prognosis, progression, immune infiltration, and therapeutic response. PFKFB3 may serve as a pivotal glycolysis regulator and mediates Sunitinib resistance in pRCC patients.

Context-dependent modification of PFKFB3 in hematopoietic stem cells promotes anaerobic glycolysis and ensures stress hematopoiesis.

Metabolic pathways are plastic and rapidly change in response to stress or perturbation. Current metabolic profiling techniques require lysis of many cells, complicating the tracking of metabolic changes over time after stress in rare cells such as hematopoietic stem cells (HSCs). Here, we aimed to identify the key metabolic enzymes that define differences in glycolytic metabolism between steady-state and stress conditions in murine HSCs and elucidate their regulatory mechanisms. Through quantitative 13C metabolic flux analysis of glucose metabolism using high-sensitivity glucose tracing and mathematical modeling, we found that HSCs activate the glycolytic rate-limiting enzyme phosphofructokinase (PFK) during proliferation and oxidative phosphorylation (OXPHOS) inhibition. Real-time measurement of ATP levels in single HSCs demonstrated that proliferative stress or OXPHOS inhibition led to accelerated glycolysis via increased activity of PFKFB3, the enzyme regulating an allosteric PFK activator, within seconds to meet ATP requirements. Furthermore, varying stresses differentially activated PFKFB3 via PRMT1-dependent methylation during proliferative stress and via AMPK-dependent phosphorylation during OXPHOS inhibition. Overexpression of Pfkfb3 induced HSC proliferation and promoted differentiated cell production, whereas inhibition or loss of Pfkfb3 suppressed them. This study reveals the flexible and multilayered regulation of HSC glycolytic metabolism to sustain hematopoiesis under stress and provides techniques to better understand the physiological metabolism of rare hematopoietic cells.

PFKFB3 regulates breast cancer tumorigenesis and Fulvestrant sensitivity by affecting ERα stability.

Estrogen receptor alpha (ERα) is expressed in approximately 70% of breast cancer cases and determines the sensitivity and effectiveness of endocrine therapy. 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase3 (PFKFB3) is a glycolytic enzyme that is highly expressed in a great many human tumors, and recent studies have shown that it plays a significant role in improving drug sensitivity. However, the role of PFKFB3 in regulating ERα expression and the underlying mechanism remains unclear. Here, we find by using immunohistochemistry (IHC) that PFKFB3 is elevated in ER-positive breast cancer and high expression of PFKFB3 resulted in a worse prognosis. In vitro and in vivo experiments verify that PFKFB3 promotes ER-positive breast cancer cell proliferation. The overexpression of PFKFB3 promotes the estrogen-independent ER-positive breast cancer growth. In an estrogen-free condition, RNA-sequencing data from MCF7 cells treated with siPFKFB3 showed enrichment of the estrogen signaling pathway, and a luciferase assay demonstrated that knockdown of PFKFB3 inhibited the ERα transcriptional activity. Mechanistically, down-regulation of PFKFB3 promotes STUB1 binding to ERα, which accelerates ERα degradation by K48-based ubiquitin linkage. Finally, growth of ER-positive breast cancer cells in vivo was more potently inhibited by fulvestrant combined with the PFKFB3 inhibitor PFK158 than for each drug alone. In conclusion, these data suggest that PFKFB3 is identified as an adverse prognosis factor for ER-positive breast cancer and plays a previously unrecognized role in the regulation of ERα stability and activity. Our results further explores an effective approach to improve fulvestrant sensitivity through the early combination with a PFKFB3 inhibitor.

PFKFB3-mediated glycolysis in hepatic stellate cells promotes liver regeneration.

Hepatic stellate cells (HSCs) perform a significant function in liver regeneration (LR) by becoming active. We propose to investigate if activated HSCs enhance glycolysis via PFKFB3, an essential glycolytic regulator, and whether targeting this pathway could be beneficial for LR. The liver and isolated HSCs of mice subjected to 2/3 partial hepatectomy (PHx) exhibited a significant rise in PFKFB3 expression, as indicated by quantitative RT-PCR analyses and Western blotting. Also, the primary HSCs of mice subjected to PHx have a significant elevation of the glycolysis level. Knocking down PFKFB3 significantly diminished the enhancement of glycolysis by PDGF in human LX2 cells. The hepatocyte proliferation in mice treated with PHx was almost completely prevented when the PFKFB3 inhibitor 3PO was administered, emerging that PFKFB3 is essential in LR. Furthermore, there was a decline in mRNA expression of immediate early genes and proinflammatory cytokines. In terms of mechanism, both the p38 MAP kinase and ERK1/2 phosphorylation in LO2 cells and LO2 proliferation were significantly reduced by the conditioned medium (CM) obtained from LX2 cells with either PFKFB3 knockdown or inhibition. Compared to the control group, isolated hepatocytes from 3PO-treated mice showed decreased p38 MAP kinase and ERK1/2 phosphorylation and proliferation. Thus, LR after PHx involves the activation of PFKFB3 in HSCs, which enhances glycolysis and promotes lactate production, thereby facilitating hepatocyte proliferation via the p38/ERK MAPK signaling pathway.

Loss of Cardiac PFKFB2 Drives Metabolic, Functional, and Electrophysiological Remodeling in the Heart.

BACKGROUND: Phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2) is a critical glycolytic regulator responsible for upregulation of glycolysis in response to insulin and adrenergic signaling. PFKFB2, the cardiac isoform of PFK-2, is degraded in the heart in the absence of insulin signaling, contributing to diabetes-induced cardiac metabolic inflexibility. However, previous studies have not examined how the loss of PFKFB2 affects global cardiac metabolism and function. METHODS AND RESULTS: To address this, we have generated a mouse model with a cardiomyocyte-specific knockout of PFKFB2 (cKO). Using 9-month-old cKO and control mice, we characterized the impacts of PFKFB2 on cardiac metabolism, function, and electrophysiology. cKO mice have a shortened life span of 9 months. Metabolically, cKO mice are characterized by increased glycolytic enzyme abundance and pyruvate dehydrogenase activity, as well as decreased mitochondrial abundance and beta oxidation, suggesting a shift toward glucose metabolism. This was supported by a decrease in the ratio of palmitoyl carnitine to pyruvate-dependent mitochondrial respiration in cKO relative to control animals. Metabolomic, proteomic, and Western blot data support the activation of ancillary glucose metabolism, including pentose phosphate and hexosamine biosynthesis pathways. Physiologically, cKO animals exhibited impaired systolic function and left ventricular dilation, represented by reduced fractional shortening and increased left ventricular internal diameter, respectively. This was accompanied by electrophysiological alterations including increased QT interval and other metrics of delayed ventricular conduction. CONCLUSIONS: Loss of PFKFB2 results in metabolic remodeling marked by cardiac ancillary pathway activation. This could delineate an underpinning of pathologic changes to mechanical and electrical function in the heart.

Down-Regulation of CPEB4 Alleviates Preeclampsia through the Inhibition of Ferroptosis by PFKFB3.

Gestational diabetes mellitus (GDM) complicated with preeclampsia can lead to polyhydramnios, ketosis. Herein, we explored that CPEB4 in cancer progression of preeclampsia and its underlying mechanism. All the serum samples were collected from patients with preeclampsia. These was the induction of CPEB4 in patients with preeclampsia. The serum of CPEB4 mRNA expression was positive correlation with Proteinuria, systolic blood pressure and diastolic blood pressure in patients. The serum of CPEB4 mRNA expression was also negative correlation with body weight of infant in patients. The serum of CPEB4 mRNA expression also was negative correlation with GPX4 level and GSH activity level in patients. The serum of CPEB4 mRNA expression was positive correlation with iron content in patients. CPEB4 gene inhibited trophoblast cell proliferation. CPEB4 gene promoted trophoblast cell ferroptosis by mitochondrial damage. CPEB4 gene induced PFKFB3 expression by the inhibition of PFKFB3 Ubiquitination. PFKFB3 inhibitor reduced the effects of CPEB4 on cell proliferation and ferroptosis of trophoblast cell. Taken together, the CPEB4 promoted trophoblast cell ferroptosis through mitochondrial damage by the induction of PFKFB3 expression, CPEB4 as an represents a potential therapeutic strategy for the treatment of preeclampsia or various types of GDM.

Triptolide restrains the growth, invasion, stemness, and glycolysis of non-small cell lung cancer cells by PFKFB2-mediated PI3K/AKT pathway.

Triptolide (TP) has been found to have anti-tumor effects. However, more potential molecular mechanisms of TP in the progression of non-small cell lung cancer (NSCLC) deserve further investigation. Cell proliferation, apoptosis, invasion, and stemness were detected by cell counting kit 8 assay, EdU assay, flow cytometry, transwell assay, and sphere formation assay. Cell glycolysis was evaluated by corresponding assay kits. 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2 (PFKFB2) expression was measured by western blot (WB), qRT-PCR and immunohistochemical staining. PI3K/AKT pathway-related markers were determined by WB. Besides, xenograft tumor model was conducted to evaluate the anti-tumor effect of TP in NSCLC. Our results revealed that TP treatment suppressed NSCLC cell proliferation, invasion, stemness, glycolysis, and enhanced apoptosis. PFKFB2 was upregulated in NSCLC tissues and cells, and its expression was decreased by TP. PFKFB2 knockdown restrained NSCLC cell functions, and its overexpression also eliminated TP-mediated NSCLC cell functions inhibition. TP decreased PFKFB2 expression to inactivate PI3K/AKT pathway. Moreover, PI3K/AKT pathway inhibitor LY294002 also could reverse the promoting effect of PFKFB2 on NSCLC cell functions. In addition, TP suppressed NSCLC tumorigenesis by inhibiting PFKFB2/PI3K/AKT pathway. In conclusion, TP exerted anti-tumor role in NSCLC, which was achieved by reducing PFKFB2 expression to inactivate PI3K/AKT pathway.

Drug-repurposing by virtual and experimental screening of PFKFB3 inhibitors for pancreatic cancer therapy.

Pancreatic cancer (PC) is the most frequently occurring cancer, with few effective treatments and a 5-year survival rate of only about 11%. It is characterized by stiff interstitium and pressure on blood vessels, leading to an increased glycolytic metabolism. PFKFB3 plays an important role in glycolysis, and its products (fructose-2,6-bisphosphate), which are allosteric PFK1 activators, limit the glycolytic rate. In this study, 14 PFKFB3 inhibitors were obtained by virtually screening the FDA-approved compound library. Subsequently, the in-vitro investigations confirmed that Lomitapide and Cabozantinib S-malate exhibit the excellent potential to inhibit PFKFB3. The combined administration of Lomitapide and Gemcitabine at a certain molar ratio indicated an enhanced anti-tumor effect in Orthotopic Pancreatic Cancer (OPC) models. This investigation provides a new treatment strategy for PC therapy.

PFKFB3-Meditated Glycolysis via the Reactive Oxygen Species-Hypoxic Inducible Factor 1α Axis Contributes to Inflammation and Proliferation of Staphylococcus aureus in Epithelial Cells.

Mastitis caused by antibiotic-resistant strains of Staphylococcus aureus is a significant concern in the livestock industry due to the economic losses it incurs. Regulating immunometabolism has emerged as a promising approach for preventing bacterial inflammation. To investigate the possibility of alleviating inflammation caused by S aureus infection by regulating host glycolysis, we subjected the murine mammary epithelial cell line (EpH4-Ev) to S aureus challenge. Our study revealed that S aureus can colonize EpH4-Ev cells and promote inflammation through hypoxic inducible factor 1α (HIF1α)-driven glycolysis. Notably, the activation of HIF1α was found to be dependent on the production of reactive oxygen species (ROS). By inhibiting PFKFB3, a key regulator in the host glycolytic pathway, we successfully modulated HIF1α-triggered metabolic reprogramming by reducing ROS production in S aureus-induced mastitis. Our findings suggest that there is a high potential for the development of novel anti-inflammatory therapies that safely inhibit the glycolytic rate-limiting enzyme PFKFB3.

PFKFB3 promotes endometriosis cell proliferation via enhancing the protein stability of ß-catenin.

Endometriosis is a common inflammatory disease in women of reproductive age and is highly associated with infertility. However, the molecular mechanism of endometriosis remains unclear. 6-Phosphofructose-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) is a key enzyme in glycolysis and plays an important regulatory role in the development of cancer. Here we found that PFKFB3 is highly expressed in endometriotic tissues. PFKFB3 promotes the proliferation and growth of endometriosis cells. Meanwhile, PFKFB3 promotes glycolysis in endometriosis cells. Furthermore, PFKFB3 promotes migration and invasion of endometriosis cells. On this basis, we found that PFKFB3 promotes epithelial-mesenchymal transition (EMT) in endometriosis cells. PFKFB3 interacts with the essential factor of EMT, ß-catenin, and promotes the protein stability of ß-catenin. In addition, the PFKFB3 inhibitor PFK-015 inhibites the growth of endometriosis cells and the development of endometrial tissue. In conclusion, our study shows that PFKFB3 plays an important role in the development of endometriosis and provides new ideas for the clinical diagnosis or treatment of endometriosis.

IL1R2 promotes retinal angiogenesis to participate in retinopathy of prematurity by activating the HIF1α/PFKFB3 pathway.

Retinopathy of prematurity (ROP) is the leading cause of blindness in children, but there is no safe and effective treatment available. Interleukin-1 receptor type 2 (IL1R2) acts as a decoy receptor for IL-1 may affect ROP progression. This study aimed to investigate the role of IL1R2 in ROP. A microglial cell model was established under hypoxia conditions and co-cultured with choroidal endothelial cells, while an oxygen-induced retinopathy (OIR) model was also established. Microglial activation and IL1R2 levels in retinal tissues were analyzed using immunofluorescence assay. Endothelial cell migration was evaluated by Transwell assay and scratch test, angiogenesis was assessed using ELISA and tube formation assay, and proliferation was evaluated by EdU assay. The HIF1α/PFKFB3 pathway was analyzed by western blot. We observed that IL1R2 expression was predicted to be upregulated in ROP and was increased in hypoxia-treated BV2 cells. Additionally, IL1R2 levels were upregulated in the retinal tissues of OIR mice and correlated with microglial activation. In vitro experiments, we found that hypoxia promoted endothelial cell migration, angiogenesis, proliferation, and activated the HIF1α/PFKFB3 pathway, which were rescued by IL1R2 knockdown. Moreover, NHWD-870 (a HIF1α/PFKFB3 pathway inhibitor) suppressed endothelial cell migration, angiogenesis, and proliferation induced by IL1R2 overexpression. In conclusion, IL1R2 facilitates the migration, angiogenesis, and proliferation of choroidal endothelial cells by activating the HIF1α/PFKFB3 pathway to regulate ROP progression.

Neuronal aerobic glycolysis exacerbates synapse loss in aging mice.

Brain consumes nearly 20% supply of energy from glucose metabolism by oxidative phosphorylation and aerobic glycolysis. Less active state of glycolytic enzymes results in a limited capacity of glycolysis in the neurons of adult brain. Here we identified that Warburg effect is enhanced in hippocampal neurons during aging. As hippocampal neurons age, lactate levels progressively increase. Notably, we observed upregulated protein levels of PFKFB3 in the hippocampus of 20-month-old mice compared to young mice, and this higher PFKFB3 expression correlated with declining memory performance in aging mice. Remarkably, in aging mice, knocking down Pfkfb3 in hippocampal neurons rescued cognitive decline and synapse loss. Conversely, Pfkfb3 overexpression in hippocampal neurons led to cognitive impairment and synapse elimination, associated with heightened glycolysis. In vitro experiments with cultured primary neurons confirmed that Pfkfb3 overexpression increased glycolysis and that glycolytic inhibition could prevent apoptotic competency in neurons. These findings underscore that glycolysis in hippocampal neurons could potentially be targeted as a therapeutic avenue to mitigate cognitive decline and preserve synaptic integrity during aging.

Inhibition of PFKFB3 Expression Stimulates Macrophage-Mediated Lymphangiogenesis Post-Acute Myocardial Infarction.

BACKGROUND: The dilation of lymphatic vessels plays a critical role in maintaining heart function, while a lack thereof could contribute to heart failure (HF), and subsequently to an acute myocardial infarction (AMI). Macrophages participate in the induction of lymphangiogenesis by secreting vascular endothelial cell growth factor C (VEGF-C), although the precise mechanism remains unclear. METHODS: Intramyocardial injections of adeno-associated viruses (AAV9) to inhibit the expression of VEGFR3 (VEGFR3 shRNA) or promote the expression of VEGFR3 (VEGFR3 ORF) in the heart; Myh6-mCherry B6 D2-tg mice and flow cytometry were used to evaluate the number of myocellular debris in the mediastinal lymph nodes; fluorescence staining and qPCR were used to evaluate fluorescence analysis; seahorse experiment was used to evaluate the level of glycolysis of macrophages; Lyz2𝐶𝑟𝑒, VEGFCfl/fl, and PFKFB3fl/fl mice were used as a model to knock out the expression of VEGF-C and PFKFB3 in macrophages. RESULTS: The escalation of VEGFR3 in cardiac tissue can facilitate the drainage of myocardial debris to the mediastinal lymph nodes, thereby improving cardiac function and reducing fibrosis after reperfusion injury. Conversely, myeloid VEGF-C deficiency displayed an increase in macrophage counts and inflammation levels following reperfusion injury. The inhibition of the critical enzyme PFKFB3 in macrophage glycolysis can stimulate the manifestation of VEGF-C in macrophages. A deficiency in myeloid PFKFB3 is associated with induced lymphangiogenesis following reperfusion injury. CONCLUSIONS: Our initial investigations suggest that the suppression of PFKFB3 expression in macrophages could potentially stimulate the production of VEGF-C in these immune cells, which in turn may facilitate lymphangiogenesis and mitigate the inflammatory effects of I/R injury.

UBC9 stabilizes PFKFB3 to promote aerobic glycolysis and proliferation of glioblastoma cells.

Cancer cells prefer to utilizing aerobic glycolysis to generate energy and anabolic metabolic intermediates for cell growth. However, whether the activities of glycolytic enzymes can be regulated by specific posttranslational modifications, such as SUMOylation, in response to oncogenic signallings, thereby promoting the Warburg effect, remain largely unclear. Here, we demonstrate that phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), a key glycolytic enzyme, interacts with SUMO-conjugating enzyme UBC9 and is SUMOylated at K302 in glioblastoma cells. Expression of UBC9, which competitively prevents the binding of ubiquitin E3 ligase APC/C to PFKFB3 and subsequent PFKFB3 polyubiquitination, increases PFKFB3 stability and expression. Importantly, EGFR activation increases the interaction between UBC9 and PFKFB3, leading to increased SUMOylation and expression of PFKFB3. This increase is blocked by inhibition of EGFR-induced AKT activation whereas expression of activate AKT by itself was sufficient to recapitulate EGF-induced effect. Knockout of PFKFB3 expression decreases EGF-enhanced lactate production and GBM cell proliferation and this decrease was fully rescued by reconstituted expression of WT PFKFB3 whereas PFKFB3 K302R mutant expression abrogates EGF- and UBC9-regulated lactate production and GBM cell proliferation. These findings reveal a previously unknown mechanism underlying the regulation of the Warburg effect through the EGFR activation-induced and UBC9-mediated SUMOylation and stabilization of PFKFB3.

Autonomous metabolic reprogramming and oxidative stress characterize endothelial dysfunction in acute myocardial infarction.

Compelling evidence has accumulated on the role of oxidative stress on the endothelial cell (EC) dysfunction in acute coronary syndrome. Unveiling the underlying metabolic determinants has been hampered by the scarcity of appropriate cell models to address cell-autonomous mechanisms of EC dysfunction. We have generated endothelial cells derived from thrombectomy specimens from patients affected with acute myocardial infarction (AMI) and conducted phenotypical and metabolic characterizations. AMI-derived endothelial cells (AMIECs) display impaired growth, migration, and tubulogenesis. Metabolically, AMIECs displayed augmented ROS and glutathione intracellular content, with a diminished glucose consumption coupled to high lactate production. In AMIECs, while PFKFB3 protein levels of were downregulated, PFKFB4 levels were upregulated, suggesting a shunting of glycolysis towards the pentose phosphate pathway, supported by upregulation of G6PD. Furthermore, the glutaminolytic enzyme GLS was upregulated in AMIECs, providing an explanation for the increase in glutathione content. Finally, AMIECs displayed a significantly higher mitochondrial membrane potential than control ECs, which, together with high ROS levels, suggests a coupled mitochondrial activity. We suggest that high mitochondrial proton coupling underlies the high production of ROS, balanced by PPP- and glutaminolysis-driven synthesis of glutathione, as a primary, cell-autonomous abnormality driving EC dysfunction in AMI.

miR-21-5p inhibits the growth of brain glioma cells through regulating the glycolysis mediated by PFKFB2.

Brain glioma is a common gynecological tumor. MicroRNA (miRNA) plays a very important role in the pathogenesis and development of tumors. It was found that glycolysis played important regulatory roles in tumor growth. The present study aims to investigate the expression pattern of miR-21-5p in brain glioma cells. We examined miR-21-5p and PFKFB2 levels in brain glioma cells via qRT-PCR. Then we performed CCK-8 and Transwell migration assays and determined glucose uptake and lactose production to unveil the properties of miR-21-5p in invasion, cell viability, along with glycolysis in brain glioma cells. Luciferase activity assay was implemented to elucidate if PFKFB2 was a miR-21-5p target gene. Western blotting and qRT-PCR were executed to further validate that miR-21-5p targeted PFKFB2. We repeated these functional assays to observe whether miR-21-5p could impede the function of PFKFB2. qRT-PCR signified that miR-21-5p was elevated in brain glioma tissues in contrast to matching adjacent normal tissues. Functional assays disclosed that elevation of miR-21-5p promoted cell viability, invasion, together with glycolysis. Luciferase assay indicated that PFKFB2 was a miR-21-5p target gene. Moreover, miR-21-inhibit could hinder cell viability, invasion, and glycolysis triggered by overexpression of PFKFB2 in brain glioma cells. miR-21-5p level is elevated in brain glioma and can impede brain glioma cell growth via regulating the glycolysis mediated by PFKFB2, thus is a potential target of treating brain glioma.

Transforming growth factor ß1 upregulates 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase-4 expression in A549 and MCF-10A cells.

Transforming growth factor ß1 (TGFß1) induces a cellular process known as epithelial-mesenchymal transition (EMT) associated with metabolic reprogramming, including enhanced glycolysis. Given the involvement of 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase (PFKFB) enzymes in glycolysis, we aimed to investigate whether TGFß1 regulates expressions of PFKFB genes and if PFKFBs are required for TGFß1-driven phenotypes. A549 and MCF-10A cell lines were used as TGFß1-driven EMT models. Messenger RNA expressions of PFKFB and EMT genes were determined by real-time quantitative polymerase chain reaction. A small interfering RNA approach was used to deplete PFKFB4 expression. A Matrigel invasion assay was conducted to assess the effect of PFKFB4 silencing on the TGFß1-enhanced invasion of A549 cells. F2,6BP levels were analyzed using an enzyme-coupled assay. Glucose and lactate concentrations were determined using colorimetric assays. TGFß1 robustly induced expression of the fourth isoform of PFKFBs, PFKFB4, in both cell lines. PFKFB4 depletion partially inhibits mesenchymal transdifferentiation caused by TGFß1 in A549 cells, as assessed by microscopy. Inductions of Snail in MCF-10A cells and Fibronectin in A549 cells and repressions of E-cadherin in both cell lines by TGFß1 are attenuated by PFKFB4 silencing. PFKFB4 silencing reduces F2,6BP and glycolytic activity, although TGFß1 alone does not affect these parameters. Finally, PFKFB4 depletion suppresses the TGFß1-driven invasion of A549 cells through Matrigel. Presented data suggest that TGFß1 induces the expression of PFKFB4 in A549 and MCF-10 cells, and PFKFB4 may be required for TGFß1-driven phenotypes such as EMT and invasion in these models.

PFKFB3-driven vascular smooth muscle cell glycolysis promotes vascular calcification via the altered FoxO3 and lactate production.

A link between increased glycolysis and vascular calcification has recently been reported, but it remains unclear how increased glycolysis contributes to vascular calcification. We therefore investigated the role of PFKFB3, a critical enzyme of glycolysis, in vascular calcification. We found that PFKFB3 expression was upregulated in calcified mouse VSMCs and arteries. We showed that expression of miR-26a-5p and miR-26b-5p in calcified mouse arteries was significantly decreased, and a negative correlation between Pfkfb3 mRNA expression and miR-26a-5p or miR-26b-5p was seen in these samples. Overexpression of miR-26a/b-5p significantly inhibited PFKFB3 expression in VSMCs. Intriguingly, pharmacological inhibition of PFKFB3 using PFK15 or knockdown of PFKFB3 ameliorated vascular calcification in vD3 -overloaded mice in vivo or attenuated high phosphate (Pi)-induced VSMC calcification in vitro. Consistently, knockdown of PFKFB3 significantly reduced glycolysis and osteogenic transdifferentiation of VSMCs, whereas overexpression of PFKFB3 in VSMCs induced the opposite effects. RNA-seq analysis and subsequent experiments revealed that silencing of PFKFB3 inhibited FoxO3 expression in VSMCs. Silencing of FoxO3 phenocopied the effects of PFKFB3 depletion on Ocn and Opg expression but not Alpl in VSMCs. Pyruvate or lactate supplementation, the product of glycolysis, reversed the PFKFB3 depletion-mediated effects on ALP activity and OPG protein expression in VSMCs. Our results reveal that blockade of PFKFB3-mediated glycolysis inhibits vascular calcification in vitro and in vivo. Mechanistically, we show that FoxO3 and lactate production are involved in PFKFB3-driven osteogenic transdifferentiation of VSMCs. PFKFB3 may be a promising therapeutic target for the treatment of vascular calcification.

cGAS-STING signaling pathway promotes hypoxia-induced renal fibrosis by regulating PFKFB3-mediated glycolysis.

Hypoxia has long been considered to play an active role in the progression of fibrosis in chronic kidney disease, but its specific mechanism is not fully understood. The stimulator of interferon genes (STING) has been a research hotspot in the fields of tumor, immunity, and infection in recent years, and its role in immune and inflammatory responses related to kidney disease has gradually attracted attention. This study mainly explores the role and mechanism of STING in hypoxia-related renal fibrosis. To address this issue, we stimulated human proximal tubular epithelial (HK-2) cells with hypoxia for 48 h to construct cell models. Meanwhile, C57BL/6J male mice were used to establish a renal fibrosis model induced by renal ischemia-reperfusion injury (IRI). In our present study, we found that the GMP-AMP synthase (cGAS)-STING signaling pathway can promote the progression of renal fibrosis after hypoxic exposure, and this effect is closely related to 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase 3 (PFKFB3)-mediated glycolysis. Furthermore, inhibition of both STING and its downstream interferon regulatory factor 3 (IRF3) reversed elevated PFKFB3 expression, thereby attenuating hypoxia-induced renal fibrosis. Taken together, our data suggest that the cGAS-STING-IRF3-PFKFB3 signaling pathway activated under hypoxia may provide new ideas and targets for the treatment of early renal fibrosis.

PFKFB3 promotes sepsis-induced acute lung injury by enhancing NET formation by CXCR4hi neutrophils.

CXCR4hi neutrophils, which are a subset of neutrophils with high CXCR4 expression, are important contributors to sepsis-induced acute lung injury (ALI). PFKFB3, a key glycolysis gene, plays an essential role in neutrophil inflammatory activation. However, the specific involvement of PFKFB3 in sepsis-induced ALI remains unclear. Here, we observed that PFKFB3 was upregulated in CXCR4hi neutrophils and facilitated sepsis-induced ALI. Mechanistically, we observed that PFKFB3 promoted sepsis-induced ALI by enhancing neutrophil extracellular trap (NET) formation by CXCR4hi neutrophils. Further study indicated that PFKFB3 promoted NET formation by upregulating glycolytic metabolism in CXCR4hi neutrophils. In summary, our study uncovered a new mechanism by which CXCR4hi neutrophils trigger sepsis-induced ALI by promoting NET formation, which is supported by PFKFB3-mediated glycolytic metabolism.