PFKFB3 Expression Research Articles

Streptococcus mutans outer membrane vesicles affect inflammasome activation and the glycolysis of macrophages

Recent studies indicate that bacterial outer membrane vesicles (OMVs) play a significant role in bacterial virulence and pathogenicity. Streptococcus mutans (S. mutans), a principal pathogen in dental caries, secretes a substantial number of OMVs. However, the impact of S. mutans OMVs on oral health and their underlying pathogenic mechanisms remain poorly understood. Macrophages were the initial innate immune cells to respond to bacterial invaders and their products. Therefore, we purified S. mutans OMVs, which stimulated macrophages. Compared to controls, RT-PCR and ELISA analyses revealed that S. mutans OMVs significantly increased the production of IL-1β, IL-6, TNF-α and IL-8, with IL-1β being notably elevated. IL-1β production and secretion are tightly regulated by the inflammasome. Western blot analyses demonstrated that S. mutans OMVs upregulated the expression of inflammasome components, including NLRP3, NLRC4, ASC and AIM2, with a marked increase in NLRP3 expression. Silencing different inflammasome components with siRNA revealed a reduction in IL-1β secretion induced by S. mutans OMVs, particularly through NLRP3. Additionally, ATP production and K+ efflux were found to be crucial for NLRP3 activation. Prolonged stimulation with S. mutans OMVs resulted in increased lactate production and elevated expression of glycolysis-related genes Glut-1, PFKFB3, and HK I, indicating that S. mutans OMVs significantly induce macrophage glycolysis. Furthermore, S. mutans OMVs were shown to enhance biofilm formation, increase S. mutans colonisation on epithelial cells, and inhibit macrophage phagocytosis, thereby improving the survival of S. mutans in the oral cavity. In summary, S. mutans OMVs promote the survival of S. mutans in the mouth through multiple mechanisms, potentially influencing the development of dental caries.

Identification of PFKFB3 as a key factor in the development of colorectal cancer and immunotherapy resistance

Resistance to immunotherapy poses a significant challenge in the treatment of colorectal cancer (CRC), and the underlying mechanisms are not fully understood. Recent studies have implicated PFKFB3, a crucial glycolytic enzyme, in shaping the tumor microenvironment in CRC. Our study aimed to systematically study the role of PFKFB3 in CRC. Bioinformatic analysis revealed that PFKFB3 expression is notably elevated in CRC tissues compared to normal counterparts. In vivo experiments confirmed that suppressing PFKFB3 reduces the tumorigenesis of CRC. We identified multiple cancer-associated pathways positively correlated with high expression of PFKFB3, such as epithelial-mesenchymal transition (EMT), hypoxia, KRAS signaling, angiogenesis, PI3K/AKT/mTOR, Hedgehog, and Notch pathways. Additionally, PFKFB3 exhibited significant correlations with various immune-related pathways, including complement, IL-2/STAT5, IL-6/JAK/STAT3, IFN-α/IFN-γ, TGF-β, and TNF-α/NF-κB, as well as several immunosuppressive cell markers found in regulatory T cells (CCR8, TGFB1, STAT5B, FOXP3), M2 macrophages (CD163, VSIG4, MS4A4A), T cell exhaustion markers (CTLA-4, PDCD1, LAG3), and PD-L1. Intriguingly, increased PFKFB3 expression was observed in PD-L1 blockade-resistant patients and was associated with shorter overall survival. In a nutshell, PFKFB3 plays an important role in CRC tumorigenesis and resistance to immunotherapy. Targeting PFKFB3 inhibits tumor formation and enhances the efficacy of immunotherapy. Our findings underscore the functions of PFKFB3 in CRC, shedding light on both cancer-related and immunosuppressive pathways.

Müller Cells Harboring Exosomal lncRNA OGRU Modulate Microglia Polarization in Diabetic Retinopathy by Serving as miRNA Sponges.

Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus which is associated with visual loss and blindness worldwide. However, the effective treatments for both early- and late-stage DR remains lacking. A streptozotocin (STZ)-induced diabetic mice model and high glucose (HG)-treated Müller cell model were established. M1/M2 microglia polarization was assessed by immunofluorescence (IF) staining and flow cytometry. Expression of lncRNA OGRU, cytokines and other key molecules were detected by qRT-PCR or western blot. ELISA assay was employed to monitor cytokine secretion. Müller cell-derived exosomes were isolated and characterized by nanopartical tracking analysis (NTA), western blot and transmission electron microscopy (TEM), and exosome uptake assay was used to monitor the intercellular transport of exosomes. Associations among lncRNA-miRNA-mRNA networks were validated by RNA pull-down and RNA immunoprecipitation (RIP) and dual luciferase assays. Increased M1 polarization but decreased M2 polarization of retinal microglia were observed in DR mice. HG-treated Müller cell-derived exosomes transported OGRU into microglia and promoted microglia polarization toward M1 phenotype. Mechanistically, OGRU served as a competing endogenous RNA (ceRNA) for miR-320-3p, miR-221-3p and miR-574-5p to regulate AR, PFKFB3 and GLUT1 expression in microglia, respectively. Loss of miR-320-3p/miR-221-3p/miR-574-5p or reinforced AR/PFKFB3/GLUT1 abrogated OGRU silencing-mediated microglia polarization in vitro. In vivo studies further showed that OGRU/miR-320-3p/AR, OGRU/miR-221-3p/PFKFB3 and OGRU/miR-574-5p/GLUT1 axes regulated microglia polarization in DR mice. Collectively, Müller cells-derived exosomal OGRU regulated microglia polarization in DR via modulating OGRU/miR-320-3p/AR, OGRU/miR-221-3p/PFKFB3 and OGRU/miR-574-5p/GLUT1 axes.

Hypoxia activates macrophage-NLRP3 inflammasome promoting atherosclerosis via PFKFB3-driven glycolysis.

The onset and progression of atherosclerosis are closely linked to the involvement of macrophages. While the contribution of NLRP3 inflammasome activation to the creation of a local highly inflammatory microenvironment is well recognized, the precise triggers remain unclear. In this study, we aimed to investigate the regulatory mechanism of NLRP3 inflammasome activation in response to hypoxia-induced glycolysis involving PFKFB3 in the development of atherosclerosis. To develop an atherosclerosis model, we selected ApoE knockout mice treated with a high-fat western diet. We then quantified the expression of HIF-1α, PFKFB3, and NLRP3. In addition, we administered the PFKFB3 inhibitor PFK158 during atherosclerosis modeling. The glycolytic activity was subsequently determined through 18F-FDG micro-PET/CT, exvivo glucose uptake, and ECAR analysis. Furthermore, we employed lipopolysaccharide (LPS) and TNF-α to induce the differentiation of bone marrow-derived macrophages (BMDMs) into M1-like phenotypes under both hypoxic and normoxic conditions. Our histological analyses revealed the accumulation of PFKFB3 in human atherosclerotic plaques, demonstrating colocalization with NLRP3 expression and macrophages. Treatment with PFK158 reduced glycolytic activity and NLRP3 inflammasome activation, thereby mitigating the occurrence of atherosclerosis. Mechanistically, hypoxia promoted glycolytic reprogramming and NLRP3 inflammasome activation in BMDMs. Subsequent blocking of either HIF-1α or PFKFB3 downregulated the NLRP3/Caspase-1/IL-1β pathway in hypoxic BMDMs. Our study demonstrated that the HIF-1α/PFKFB3/NLRP3 axis serves as a crucial mechanism for macrophage inflammation activation in the emergence of atherosclerosis. The therapeutic potential of PFKFB3 inhibition may represent a promising strategy for atheroprotection.

Glycolytic PFKFB3 and Glycogenic UGP2 Axis Regulates Perfusion Recovery in Experimental Hind Limb Ischemia.

Despite being in an oxygen-rich environment, endothelial cells (ECs) use anaerobic glycolysis (Warburg effect) as the primary metabolic pathway for cellular energy needs. PFKFB (6-phosphofructo-2-kinase/fructose-2,6-biphosphatase)-3 regulates a critical enzymatic checkpoint in glycolysis and has been shown to induce angiogenesis. This study builds on our efforts to determine the metabolic regulation of ischemic angiogenesis and perfusion recovery in the ischemic muscle. Hypoxia serum starvation (HSS) was used as an in vitro peripheral artery disease (PAD) model, and hind limb ischemia by femoral artery ligation and resection was used as a preclinical PAD model. Despite increasing PFKFB3-dependent glycolysis, HSS significantly decreased the angiogenic capacity of ischemic ECs. Interestingly, inhibiting PFKFB3 significantly induced the angiogenic capacity of HSS-ECs. Since ischemia induced a significant in PFKFB3 levels in hind limb ischemia muscle versus nonischemic, we wanted to determine whether glucose bioavailability (rather than PFKFB3 expression) in the ischemic muscle is a limiting factor behind impaired angiogenesis. However, treating the ischemic muscle with intramuscular delivery of D-glucose or L-glucose (osmolar control) showed no significant differences in the perfusion recovery, indicating that glucose bioavailability is not a limiting factor to induce ischemic angiogenesis in experimental PAD. Unexpectedly, we found that shRNA-mediated PFKFB3 inhibition in the ischemic muscle resulted in an increased perfusion recovery and higher vascular density compared with control shRNA (consistent with the increased angiogenic capacity of PFKFB3 silenced HSS-ECs). Based on these data, we hypothesized that inhibiting HSS-induced PFKFB3 expression/levels in ischemic ECs activates alternative metabolic pathways that revascularize the ischemic muscle in experimental PAD. A comprehensive glucose metabolic gene qPCR arrays in PFKFB3 silenced HSS-ECs, and PFKFB3-knock-down ischemic muscle versus respective controls identified UGP2 (uridine diphosphate-glucose pyrophosphorylase 2), a regulator of protein glycosylation and glycogen synthesis, is induced upon PFKFB3 inhibition in vitro and in vivo. Antibody-mediated inhibition of UGP2 in the ischemic muscle significantly impaired perfusion recovery versus IgG control. Mechanistically, supplementing uridine diphosphate-glucose, a metabolite of UGP2 activity, significantly induced HSS-EC angiogenic capacity in vitro and enhanced perfusion recovery in vivo by increasing protein glycosylation (but not glycogen synthesis). Our data present that inhibition of maladaptive PFKFB3-driven glycolysis in HSS-ECs is necessary to promote the UGP2-uridine diphosphate-glucose axis that enhances ischemic angiogenesis and perfusion recovery in experimental PAD.

Reduced endometrial glycolysis concomitant with increased lesional fibrosis in patients with adenomyosis who complained of heavy menstrual bleeding

RESEARCH QUESTIONWhat role, if any, does the extent of lesional fibrosis play in adenomyosis-associated heavy menstrual bleeding (ADM-HMB)? DESIGNForty-eight patients with ADM-HMB were recruited, among them 25 reported moderate/heavy bleeding (MHB) and the remaining 23, excessive bleeding (EXB). The full-thickness uterine tissue columns were processed for Masson trichrome staining and immunohistochemistry analyses. The levels of HIF-1α, GLUT1, HK2, PFKFB3 and PKM2—proteins critically involved in glycolysis—in endometrial epithelial cells cultured on substrates of different stiffness, and the levels of glycolysis were quantitated. A mouse experiment with induced adenomyosis and simulated menstrual bleeding was conducted to assess the impact of adenomyosis on immunoexpression of proteins involved in glycolysis and inflammation as well as on endometrial repair and bleeding. RESULTSThe endometrial staining of HIF-1α, GLUT1, HK2, PFKFB3 and PKM2 was significantly lower in the EXB group as compared with MHB patients, concomitant with higher extent of fibrosis. The expression of HIF-1α, GLUT1, HK2, PFKFB3 and PKM2 was significantly reduced when endometrial epithelial cells were cultured in stiff substrate, concomitant with reduced glycolysis. Mice with induced adenomyosis exhibited reduced immunoexpression of Hif-1α, as well as those proteins each of which plays a vital, rate-limiting role in different steps of the glycolysis pathway, such as Glut1, Hk2, Pfkfb3 and Pkm2, and elevated fibrosis in endometrium, concomitant with disrupted endometrial repair and more bleeding. CONCLUSIONSLesional fibrosis results in reduced endometrial glycolysis in eutopic endometrium and subsequent imbalance in pro- and anti-inflammatory response, leading to ADM-HMB.

Expression and prognostic analysis of PFKFB4 in oral squamous cell carcinoma.

Fructose-6-phosphate 2-kinase/fructose-2,6-bisphosphatase 4 (PFKFB4) is a crucial enzyme in the glycolysis pathway, possessing both kinase and phosphatase capabilities. Although it has emerged as an important oncogene in various cancer types, its function in oral squamous cell carcinoma (OSCC) is still not well understood. In our research, PFKFB4 expression was assessed via immunohistochemical (IHC) staining of tissue microarrays and OSCC patient specimens. The transcriptional expression of PFKFB4 in OSCC was analyzed by utilizing The Cancer Genome Atlas (TCGA) dataset. Correlation between PFKFB4 expression and clinicopathological features was examined using the χ2 test. Prognostic investigation of PFKFB4 was conducted via Kaplan-Meier and Cox analyses. PFKFB4 levels were notably elevated in OSCC samples in comparison to adjacent normal tissues (P < 0.001). Elevated PFKFB4 expression was associated with higher histologic grade (P = 0.0438), higher T stage (P = 0.031), and more advanced clinical stage (P = 0.0063). The ROC curve demonstrated the diagnostic potential of PFKFB4 (AUC = 0.827). Increased levels of PFKFB4 were linked to decreased overall survival (OS) (P = 0.04), poorer disease-specific survival (DSS) (P = 0.04), and shorter progression-free interval (PFI) (P < 0.001). PFKFB4 expression was identified as an independent risk factor for OS based on Cox regression analysis [hazard ratio (HR) = 1.517, P = 0.044)]. An OS nomogram was constructed with a concordance index of 0.690. Our findings reveal that upregulated PFKFB4 expression in OSCC tissues could serve as a potential prognostic biomarker.

Immunometabolic alteration of CD4+ T cells in the pathogenesis of primary Sjögren’s syndrome

Primary Sjögren’s syndrome (pSS) is a prevalent autoimmune disorder wherein CD4+ T cells play a pivotal role in its pathogenesis. However, the underlying mechanisms driving the hyperactivity of CD4+ T cells in pSS remain poorly understood. This study aimed to investigate the potential role of immunometabolic alterations in driving the hyperactivity of CD4+ T cells in pSS. We employed Seahorse XF assay to evaluate the metabolic phenotype of CD4+ T cells, conducted flow cytometry to assess the effector function and differentiation of CD4+ T cells and measured the level of intracellular reactive oxygen species (ROS). Additionally, transcriptome sequencing, PCR, and Western blotting were utilized to examine the expression of glycolytic genes. Our investigation revealed that activated CD4+ T cells from pSS patients exhibited elevated aerobic glycolysis, rather than oxidative phosphorylation, resulting in excessive production of IFN-γ and IL-17A. Inhibition of glycolysis by 2-Deoxy-D-glucose reduced the expression of IFN-γ and IL-17A in activated CD4+ T cells and mitigated the differentiation of Th1 and Th17 cells. Furthermore, the expression of glycolytic genes, including CD3E, CD28, PIK3CA, AKT1, mTOR, MYC, LDHA, PFKL, PFKFB3, and PFKFB4, was upregulated in activated CD4+ T cells from pSS patients. Specifically, the expression and activity of LDHA were enhanced, contributing to an increased level of intracellular ROS. Targeting LDHA with FX-11 or inhibiting ROS with N-acetyl-cysteine had a similar effect on reversing the dysfunction of activated CD4+ T cells from pSS patients. Our study unveils heightened aerobic glycolysis in activated CD4+ T cells from pSS patients, and inhibition of glycolysis or its metabolite normalizes the dysfunction of activated CD4+ T cells. These findings suggest that aerobic glycolysis may be a promising therapeutic target for the treatment of pSS.

Genomic Deletion of PFKFB3 Decreases In Vivo Tumorigenesis.

Rapidly proliferative processes in mammalian tissues including tumorigenesis and embryogenesis rely on the glycolytic pathway for energy and biosynthetic precursors. The enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3) plays an important regulatory role in glycolysis by activating the key rate-limiting glycolytic enzyme, 6-phosphofructo-1-kinase (PFK-1). We have previously determined that decreased PFKFB3 expression reduced glycolysis and growth in transformed cells in vitro and suppressed xenograft growth in vivo. In earlier studies, we created a constitutive knockout mouse to interrogate the function of PFKFB3 in vivo but failed to generate homozygous offspring due to the requirement for PFKFB3 for embryogenesis. We have now developed a novel transgenic mouse model that exhibits inducible homozygous pan-tissue Pfkfb3 gene deletion (Pfkfb3fl/fl). We have induced Pfkfb3 genomic deletion in these mice and found that it effectively decreased PFKFB3 expression and activity. To evaluate the functional consequences of Pfkfb3 deletion in vivo, we crossed Cre-bearing Pfkfb3fl/fl mice with oncogene-driven tumor models and found that Pfkfb3 deletion markedly decreased their glucose uptake and growth. In summary, our studies reveal a critical regulatory function for PFKFB3 in glycolysis and tumorigenesis in vivo and characterize an effective and powerful model for further investigation of its role in multiple biological processes.

Effect of transcription factor WT1 on triple-negative breast cancer metastasis through PFKFB4-mediated glycolysis.

e13145 Background: Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer with a high probability of metastasis as well as a lack of specific targets and targeted therapeutics. Preliminary study suggested that Wilms' tumor gene 1 (WT1) is highly expressed in breast cancer patients with poor prognosis and may promote TNBC metastasis, but the underlying mechanism remains poorly defined. Methods: WT1 expression was evaluated by immunohistochemistry (IHC) in breast cancer patients. Kaplan–Meier survival analysis was performed to assess the prognostic significance of WT1 expression. WT1 was silenced in MDA-MB-231 and BT549 cells or overexpressed in HCC1806 cells. qRT-PCR and Western blot were used to detect the WT1 expression in tissues and cells. Wound healing assays, transwell assays and 3D spheroid assays were used to examine the migration and invasion abilities in TNBC cells. The lung metastasis model of mice was used to evaluate metastasis of TNBC in vivo. Chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) and transcriptome sequencing (RNA-seq) were performed to find PFKFB4, a downstream target gene for WT1. ChIP-PCR and dual-luciferase reporter assays were used to explore the transcriptional regulation of PFKFB4 by WT1. Seahorse XF glycolysis stress assay, glucose uptake assay, and lactate production assay were used to investigate the role of WT1 in regulating glycolysis metabolites. Results: WT1 was highly expressed in TNBC and correlated to poor prognosis in TNBC patients. Functional assays revealed that WT1 promoted TNBC cell metastasis in vitro and in vivo. Our mechanistic investigations demonstrated that WT1 promoted TNBC cells migration and invasion by transcriptionally activating the expression of PFKFB4.This action leaded to increased glycolytic capacity, glucose uptake, and lactate production in cancer cells, therefore promoting metastasis of TNBC. Clinically, the combined expression of WT1 and PFKFB4 provides a reliable predictive biomarker for the prognosis of TNBC patients. Conclusions: Our findings reveal a molecular mechanism of WT1 promoting TNBC metastasis, which provides new targets for the precision treatment of TNBC and new perspectives for the development of targeted metabolic anticancer drugs.

Weak neuronal glycolysis sustains cognition and organismal fitness

The energy cost of neuronal activity is mainly sustained by glucose1,2. However, in an apparent paradox, neurons modestly metabolize glucose through glycolysis3–6, a circumstance that can be accounted for by the constant degradation of 6-phosphofructo-2-kinase–fructose-2,6-bisphosphatase-3 (PFKFB3)3,7,8, a key glycolysis-promoting enzyme. To evaluate the in vivo physiological importance of this hypoglycolytic metabolism, here we genetically engineered mice with their neurons transformed into active glycolytic cells through Pfkfb3 expression. In vivo molecular, biochemical and metabolic flux analyses of these neurons revealed an accumulation of anomalous mitochondria, complex I disassembly, bioenergetic deficiency and mitochondrial redox stress. Notably, glycolysis-mediated nicotinamide adenine dinucleotide (NAD+) reduction impaired sirtuin-dependent autophagy. Furthermore, these mice displayed cognitive decline and a metabolic syndrome that was mimicked by confining Pfkfb3 expression to hypothalamic neurons. Neuron-specific genetic ablation of mitochondrial redox stress or brain NAD+ restoration corrected these behavioural alterations. Thus, the weak glycolytic nature of neurons is required to sustain higher-order organismal functions.

The glycolytic enzyme PFKFB3 drives kidney fibrosis through promoting histone lactylation-mediated NF-κB family activation

Persistently elevated glycolysis in kidney has been demonstrated to promote chronic kidney disease (CKD). However, the underlying mechanism remains largely unclear. Here, we observed that 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), a key glycolytic enzyme, was remarkably induced in kidney proximal tubular cells (PTCs) following ischemia-reperfusion injury (IRI) in mice, as well as in multiple etiologies of patients with CKD. PFKFB3 expression was positively correlated with the severity of kidney fibrosis. Moreover, patients with CKD and mice exhibited increased urinary lactate/creatine levels and kidney lactate, respectively. PTCs-specific deletion of PFKFB3 significantly reduced kidney lactate levels, mitigated inflammation and fibrosis, and preserved kidney function in the IRI mouse model. Similar protective effects were observed in mice with heterozygous deficiency of PFKFB3 or those treated with a PFKFB3 inhibitor. Mechanistically, lactate derived from PFKFB3-mediated tubular glycolytic reprogramming markedly enhanced histone lactylation, particularly H4K12la, which was enriched at the promoter of NF- κB signaling genes like Ikbkb, Rela, and Relb, activating their transcription and facilitating the inflammatory response. Further, PTCs-specific deletion of PFKFB3 inhibited the activation of IKKβ, I κ B α, and p65 in the IRI kidneys. Moreover, increased H4K12la levels were positively correlated with kidney inflammation and fibrosis in patients with CKD. These findings suggest that tubular PFKFB3 may play a dual role in enhancing NF- κB signaling by promoting both H4K12la-mediated gene transcription and its activation. Thus, targeting the PFKFB3-mediated NF- κB signaling pathway in kidney tubular cells could be a novel strategy for CKD therapy.

MiR-106a-5p targets PFKFB3 and improves sepsis through regulating macrophage pyroptosis and inflammatory response

The enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase isoform 3 (PFKFB3) is a critical regulator of glycolysis and plays a key role in modulating the inflammatory response, thereby contributing to the development of inflammatory diseases such as sepsis. Despite its importance, the development of strategies to target PFKFB3 in the context of sepsis remains challenging. In this study, we employed a microRNA-based approach to decrease PFKFB3 expression. Through multiple meta-analyses, we observed a downregulation of miR-106a-5p expression and an upregulation of PFKFB3 expression in clinical sepsis samples. These changes were also confirmed in blood monocytes from patients with early sepsis and from a mouse model of lipopolysaccharide (LPS)-induced sepsis. Overexpression of miR-106a-5p significantly decreased the LPS-induced increase in glycolytic capacity, inflammatory response, and pyroptosis in macrophages. Mechanistically, we identified PFKFB3 as a direct target protein of miR-106a-5p and demonstrated its essential role in LPS-induced pyroptosis and inflammatory response in macrophages. Furthermore, treatment with agomir-miR-106a-5p conferred a protective effect in an LPS mouse model of sepsis, but this effect was attenuated in myeloid-specific Pfkfb3 knockout mice. These findings indicate that miR-106a-5p inhibits macrophage pyroptosis and inflammatory response in sepsis by regulating PFKFB3-mediated glucose metabolism, representing a potential therapeutic option for the treatment of sepsis.

Abstract 2036: Prognostic Impact Of Pfkfb3 Expression In Endothelial Cells Insights From Peripheral Arterial Disease Patients And The Effects Of Supervised Exercise

Background: Glycolysis constitutes 85% of ATP production in endothelial cells (ECs). Although upregulating PFKFB3 (6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3), the rate-controlling enzyme for EC glycolysis, has been considered a mean to induce angiogenesis, our group found this approach ineffective or even harmful in pre-clinical peripheral arterial disease (PAD) models. However, no EC specific PFKFB3 data in human PAD patients exists. Hypothesis: EC PFKFB3 upregulation is associated with poor prognosis in PAD patients. Goal: Assess PFKFB3 in ECs and correlate its’ expression with PAD clinical presentation and outcome. Methods: CD31 (EC marker) and PFKFB3 immunostaining was performed on age-matched gastrocnemius (GA) muscle sections from healthy adult control (HA), PAD patients with intermittent claudication (IC; patients experience pain during activity), and patients with chronic limb threatening ischemia (CLTI; the most severe presentation of PAD -patients experience pain at rest with increased risk of ulcers, gangrene, and amputation). A similar approach was used on GA muscle sections from PAD patients before and after 3 weeks of supervised exercise. qPCR was done on flow sorted live CD56-CD31+ EC population from HA and CLTI GA muscle biopsies, for CD31 and PFKFB3 expression. Results: The IC presentation did not increase the %PFKFB3 + ECs (17.08 ± 1.19 vs. 14.40 ± 2.32 SEM, n=6-7/group, p= 0.69) from HA. However, in CLTI tissues, the %PFKFB3 + ECs increased vs both HA (42.01 ± 4.32 SEM vs. 14.40 ± 2.327 SEM, n=7/group, p= 0.0025) and IC (42.01 ± 4.32 SEM vs. 17.08 ± 1.19 SEM, n=6-7/group, p= 0.01). Furthermore, qPCR analysis of PFKFB3 expression in flow sorted CD56-CD31+ EC fraction from CLTI vs. HA (1.855 ± 0.084 SEM vs. 1 ± 0.1768 SEM, n=4/group, P= 0.0052). Three weeks of supervised exercise in PAD patients, with tolerance for activity, decreased the %PFKFB3 + ECs compared vs. pre-exercise values (7.02 ± 1.74 SEM vs. 18.24 ± 2.15 SEM, n= 4 /group, p= 0.0077) respectively. Conclusion: In humans with PAD, higher EC expression of PFKFB3 + uniquely associated with CLTI, but not the IC presentation. Supervised exercise, the only non-surgical approved method to improve functional performance and angiogenesis in PAD patients, reduced EC PFKFB3 expression.

The predictive value of PFKFB3 in bladder cancer prognosis

6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-3 (PFKFB3) influences cancer progression via participating in tumor aerobic glycolysis. In this study, we aimed to evaluate the prognostic significance of PFKFB3 in bladder cancer (BLCA) patients by analyzing a combination of publicly available databases, clinical patient data, and bladder tumor samples from our hospital. Single-cell and bulk RNA-seq data of bladder cancer, obtained from ENA, GEO, and TCGA databases, were utilized for our analysis. The results indicated that PFKFB3 mRNA expression was markedly elevated in bladder cancer compared to paired normal tissue. Furthermore, BLCA patients with high PFKFB3 expression exhibited a significantly worse prognosis (P < 0.05). To validate these findings, clinical data and immunohistochemistry staining were performed on specimens obtained from 89 BLCA patients who underwent radical cystectomy at either Qingdao University Affiliated Hospital or Peking Union Medical College Hospital. The findings from this verification process confirmed that high expression of PFKFB3 serves as a biomarker for predicting worse prognosis in BLCA patients (OR: 2.462, 95 % CI: 1.202–5.042, P = 0.012). To facilitate clinical application, we developed a nomogram based on four variables, including PFKFB3 expression, to predict the survival of BLCA patients. Importantly, this nomogram demonstrated a low mean prediction error of 0.03. Taken together, our findings suggest that PFKFB3 has the potential to serve as both a prognostic biomarker and a therapeutic target for BLCA patients.

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.

Endothelial nucleotide-binding oligomerization domain-like receptor protein 3 inflammasome regulation in atherosclerosis.

The activation of nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome in endothelial cells (ECs) contributes to vascular inflammation in atherosclerosis. Considering the high glycolytic rate of ECs, we delineated whether and how glycolysis determines endothelial NLRP3 inflammasome activation in atherosclerosis. Our results demonstrated a significant up-regulation of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), a key regulator of glycolysis, in human and mouse atherosclerotic endothelium, which positively correlated with NLRP3 levels. Atherosclerotic stimuli up-regulated endothelial PFKFB3 expression via sterol regulatory element-binding protein 2 (SREBP2) transactivation. EC-selective haplodeficiency of Pfkfb3 in Apoe-/- mice resulted in reduced endothelial NLRP3 inflammasome activation and attenuation of atherogenesis. Mechanistic investigations revealed that PFKFB3-driven glycolysis increased the NADH content and induced oligomerization of C-terminal binding protein 1 (CtBP1), an NADH-sensitive transcriptional co-repressor. The monomer form, but not the oligomer form, of CtBP1 was found to associate with the transcriptional repressor Forkhead box P1 (FOXP1) and acted as a transrepressor of inflammasome components, including NLRP3, caspase-1, and interleukin-1β (IL-1β). Interfering with NADH-induced CtBP1 oligomerization restored its binding to FOXP1 and inhibited the glycolysis-dependent up-regulation of NLRP3, Caspase-1, and IL-1β. Additionally, EC-specific overexpression of NADH-insensitive CtBP1 alleviates atherosclerosis. Our findings highlight the existence of a glycolysis-dependent NADH/CtBP/FOXP1-transrepression pathway that regulates endothelial NLRP3 inflammasome activation in atherogenesis. This pathway represents a potential target for selective PFKFB3 inhibitors or strategies aimed at disrupting CtBP1 oligomerization to modulate atherosclerosis.

Pseudomonas Aeruginosa Affects the Function of Pulmonary Vascular Endothelial Cells

Objective To investigate the impact of Pseudomonas aeruginosa(PA) infection on the function of pulmonary vascular endothelial cells,and explore the mechanism of this bacterium in exacerbating lung inflammation in mice. Methods Two hours after human lung microvascular endothelial cell(HULEC-5a) were infected with the PA strain PAO1,the mRNA levels of autophagy-related gene 5(ATG5),6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3(PFKFB3),and calcium adhesion protein 5(CDH5) were determined by reverse transcription real-time fluorescent quantitative PCR(RT-qPCR).The protein levels of ATG5,PFKFB3,and vascular endothelial calcium adhesion protein(VE-cadherin) were detected by immunofluorescence.After the expression of ATG5 and PFKFB3 was respectively knocked down by small interfering RNA(siRNA),RT-qPCR was employed to measure the mRNA levels of ATG5,PFKFB3,and CDH5,and immunofluorescence to detect the protein levels of PFKFB3 and VE-cadherin.In addition,the lactate assay kit was used to determine the level of lactate in the cells.After mice were infected with PAO1,lung inflammation was assessed through histopathological section staining.Confocal microscopy was employed to capture and analyze fluorescence-labeled PFKFB3 and VE-cadherin in endothelial cells. Results Compared with the control group,the HULEC-5a cells infected with PAO1 showed up-regulated mRNA and protein levels of PFKFB3(all P<0.05),down-regulated mRNA level of CDH5(P=0.023),disrupted continuity and down-regulated protein level of VE-cadherin(P<0.001),and elevated lactate level(P=0.017).Compared with PAO1-infected HULEC-5a cells,knocking down PFKFB3 led to the up-regulated mRNA level of CDH5(P=0.043),lowered lactate level(P=0.047),and restored continuity of VE-cadherin;knocking down ATG5 led to up-regulated mRNA and protein levels of PFKFB3(P=0.013 and P=0.003),elevated lactate level(P=0.015),and down-regulated mRNA level of CDH5(P=0.020) and protein level of VE-cadherin(P=0.001).The HE staining results showed obvious red blood cell leakage,inflammatory cell infiltration,alveolar septal widening,and partial detachment of vascular endothelial cells in the alveoli of PA-infected mice.Immunofluorescence staining showed up-regulated expression of PFKFB3 and decreased fluorescence signal of VE-cadherin in endothelial cells of infected mice compared with normal mice. Conclusion PA may regulate the PFKFB3 pathway via AGT5 to disrupt the function of pulmonary vascular endothelial cells,thereby exacerbating the inflammation in the lungs of mice.

M6A methylation of FKFB3 reduced pyroptosis of gastric cancer by NLRP3.

Gastric cancer is a kind of malignant tumor that seriously endangers human life and health. Its incidence rate and mortality rate are among the highest in the global malignant tumors. Therefore, this study explored the role of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) in the progression of gastric cancer and its underlying mechanism. Patients with gastric cancer were collected, and human GC cell lines (stomach gastric carcinoma 7901, stomach gastric carcinoma 823 , human gastric carcinoma cell line 803 and adenocarcinoma gastric stomach) were used in this study. We utilized glucose consumption, cell migration, and ELISA assay kits to investigate the function of GC. To understand its mechanism, we employed quantitative PCR (qPCR), western blot, and m6A methylated RNA immunoprecipitation assay. FKFB3 protein expression levels in patients with gastric cancer were increased. The induction of PFKFB3 mRNA expression levels in patients with gastric cancer or gastric cancer cell lines. Gastric cancer patients with high PFKFB3 expression had a lower survival rate. PFKFB3 high expression possessed the probability of pathological stage, lymph node metastasis or distant metastasis in patients with gastric cancer. PFKFB3 upregulation promoted cancer progression and Warburg effect progression of gastric cancer. PFKFB3 upregulation reduced pyroptosis and suppressed nucleotidebinding domain, leucinerich repeat containing protein 3-induced pyroptosis of gastric cancer. M6A-forming enzyme methyltransferase-like 3 increased PFKFB3 stability. Taken together, the M6A-forming enzyme methyltransferase-like 3 increased PFKFB3 stability and reduced pyroptosis in the model of gastric cancer through the Warburg effect. The PFKFB3 gene represents a potential therapeutic strategy for the treatment of gastric cancer.