Nuclear PKM2 regulates β-catenin transactivation upon EGFR activation

Maintaining moderate levels of hypochlorous acid promotes neural stem cell proliferation and differentiation in the recovery phase of stroke

JOURNAL/nrgr/04.03/01300535-202503000-00029/figure1/v/2024-06-17T092413Z/r/image-tiff It has been shown clinically that continuous removal of ischemia/reperfusion-induced reactive oxygen species is not conducive to the recovery of late stroke. Indeed, previous studies have shown that excessive increases in hypochlorous acid after stroke can cause severe damage to brain tissue. Our previous studies have found that a small amount of hypochlorous acid still exists in the later stage of stroke, but its specific role and mechanism are currently unclear. To simulate stroke in vivo, a middle cerebral artery occlusion rat model was established, with an oxygen-glucose deprivation/reoxygenation model established in vitro to mimic stroke. We found that in the early stage (within 24 hours) of ischemic stroke, neutrophils produced a large amount of hypochlorous acid, while in the recovery phase (10 days after stroke), microglia were activated and produced a small amount of hypochlorous acid. Further, in acute stroke in rats, hypochlorous acid production was prevented using a hypochlorous acid scavenger, taurine, or myeloperoxidase inhibitor, 4-aminobenzoic acid hydrazide. Our results showed that high levels of hypochlorous acid (200 μM) induced neuronal apoptosis after oxygen/glucose deprivation/reoxygenation. However, in the recovery phase of the middle cerebral artery occlusion model, a moderate level of hypochlorous acid promoted the proliferation and differentiation of neural stem cells into neurons and astrocytes. This suggests that hypochlorous acid plays different roles at different phases of cerebral ischemia/reperfusion injury. Lower levels of hypochlorous acid (5 and 100 μM) promoted nuclear translocation of β-catenin. By transfection of single-site mutation plasmids, we found that hypochlorous acid induced chlorination of the β-catenin tyrosine 30 residue, which promoted nuclear translocation. Altogether, our study indicates that maintaining low levels of hypochlorous acid plays a key role in the recovery of neurological function.

Suppressing nuclear translocation of microglial PKM2 confers neuroprotection via downregulation of neuroinflammation after mouse cerebral ischemia-reperfusion injury

Pyruvate kinase M2 (PKM2) is a key metabolic enzyme. Yet, its role in cerebral ischemia injury remains unclear. In this study we demonstrated that PKM2 expression was increased in the microglia after mouse cerebral ischemia-reperfusion (I/R) injury. We found that microglial polarization-mediated pro-inflammatory effect was mediated by PKM2 after cerebral I/R. Mechanistically, our results revealed that nuclear PKM2 mediated ischemia-induced microglial polarization through association with acetyl-H3K9. Hif-1α mediated the effect of nuclear PKM2/histone H3 on microglial polarization. PKM2-dependent Histone H3/Hif-1α modifications contributed the expression of CCL2 and induced up-regulation of microglial polarization in peri-infarct, resulting in neuroinflammation. Inhibiting nuclear translocation of microglial PKM2 reduced ischemia-induced pro-inflammation and promoted neuronal survival. Together, this study identifies nucleus PKM2 as a crucial mediator for regulating ischemia-induced neuroinflammation, suggesting PKM2 as a potential therapeutic target in ischemic stroke.

Fructose-1,6-bisphosphatase 1 dephosphorylates and inhibits TERT for tumor suppression

Telomere dysfunction is intricately linked to the aging process and stands out as a prominent cancer hallmark. Here we demonstrate that telomerase activity is differentially regulated in cancer and normal cells depending on the expression status of fructose-1,6-bisphosphatase 1 (FBP1). In FBP1-expressing cells, FBP1 directly interacts with and dephosphorylates telomerase reverse transcriptase (TERT) at Ser227. Dephosphorylated TERT fails to translocate into the nucleus, leading to the inhibition of telomerase activity, reduction in telomere lengths, enhanced senescence and suppressed tumor cell proliferation and growth in mice. Lipid nanoparticle-mediated delivery of FBP1 mRNA inhibits liver tumor growth. Additionally, FBP1 expression levels inversely correlate with TERT pSer227 levels in renal and hepatocellular carcinoma specimens and with poor prognosis of the patients. These findings demonstrate that FBP1 governs cell immortality through its protein phosphatase activity and uncover a unique telomerase regulation in tumor cells attributed to the downregulation or deficiency of FBP1 expression.

Delta-Like Homolog 2 Facilitates Malignancy of Hepatocellular Carcinoma via Activating EGFR/PKM2 Signaling Pathway

Delta-like homolog 2 (DLK2) plays a crucial role in adipogenesis, chondrogenic differentiation, and the progression of certain cancers. However, the key roles of DLK2 underlying the progression of hepatocellular carcinoma (HCC) remain ambiguous. In the current study, we demonstrate that DLK2 is upregulated in HCC, significantly correlated with clinicopathological variables and serves as an independent diagnostic marker. Functional assays reveal that DLK2 facilitates malignant progression of HCC in vitro and in vivo models. Mechanistically, DLK2 binds to EGFR resulting in its auto-phosphorylation, which activates NK-κB pathway leading to P65-dependent transcriptional upregulation of PKM2. Furthermore, that elevates both enzyme-dependent and -independent activities of PKM2 contributing to cancer proliferation and metastasis. In summary, our findings demonstrate a novel pro-tumoral role and mechanism of DLK2 in the regulation of HCC malignant progression, suggesting its potential as a clinical diagnostic marker and therapeutic target.

Sirtuin 1/sirtuin 3 are robust lysine delactylases and sirtuin 1-mediated delactylation regulates glycolysis

Lysine lactylation (Kla), an epigenetic mark triggered by lactate during glycolysis, including the Warburg effect, bridges metabolism and gene regulation. Enzymes such as p300 and HDAC1/3 have been pivotal in deciphering the regulatory dynamics of Kla, though questions about additional regulatory enzymes, their specific Kla substrates, and the underlying functional mechanisms persist. Here, we identify SIRT1 and SIRT3 as key "erasers" of Kla, shedding light on their selective regulation of both histone and non-histone proteins. Proteomic analysis in SIRT1/SIRT3 knockout HepG2 cells reveals distinct substrate specificities toward Kla, highlighting their unique roles in cellular signaling. Notably, we highlight the role of specific Kla modifications, such as those on the M2 splice isoform of pyruvate kinase (PKM2), in modulating metabolic pathways and cell proliferation, thereby expanding Kla's recognized functions beyond epigenetics. Therefore, this study deepens our understanding of Kla's functional mechanisms and broadens its biological significance.

USP28 promotes tumor progression and glycolysis by stabilizing PKM2/Hif1-α in cholangiocarcinoma

BACKGROUND

Ubiquitination is one of the important modification of proteins which can be reversed by deubiquitinating enzymes (DUBs). Ubiquitin specific protease 28 (USP28) belongs to the deubiquitinase family, which plays a cancer-promoting function in many types of cancers such as pancreatic cancer and breast cancer. So far, the molecular function and significance of USP 28 in cholangiocarcinoma remain unclear.

METHODS

In this study, we evaluated the expression of USP28 using tissue microarray (TMA), reverse transcription polymerase chain reaction (qRT-PCR), and online databases. We investigated the effect of USP28 on the progression of CCA through in vitro and in vivo functional experiments. In addition, we explored downstream molecular pathways using Western blotting (WB), immunofluorescence (IF), and mass spectrometry techniques.

RESULTS

Here, we found that cholangiocarcinoma tissue had higher USP 28 expression than normal bile duct tissue, and that high USP 28 levels were significantly associated with a malignant phenotype and poorer prognosis in cholangiocarcinoma patients. Both in vitro and in vivo, USP28 could mediate the deubiquitination of PKM2, thereby activating the downstream Hif1-α signaling pathway, promoting glycolysis and energy supply, and finally promoting tumor progression.

CONCLUSION

In summary, USP28 activated downstream Hif1-α by reducing the ubiquitination level of PKM2, furthermore, promoting the level of glycolysis in CCA cells for tumor progression.

Pin1: Advances in pancreatic cancer therapeutic potential and inhibitors research

The peptidyl-prolyl cis/trans isomerase NIMA-interaction 1 (Pin1) catalyzes the transition of the proline ring from the cis to trans conformation, resulting in conformational and functional changes in proteins that are regulated by proline-guided serine/threonine phosphorylation. In recent years, Pin1 has emerged as a novel molecular target for the diagnosis and treatment of various malignant tumors. Notably, it has been found that Pin1 is highly expressed in pancreatic cancer. This article focuses on the mechanisms by which Pin1 orchestrates multiple oncogenic functions in the development of pancreatic cancer. By exploring the intricate interactions between Pin1 and the pancreatic tumor microenvironment, we provide an overview of Pin1's role in modifying glycolytic metabolism, redox balance, and the hypoxic microenvironment of pancreatic cancer. Furthermore, we summarize the potential anticancer effects of Pin1 inhibitors, aiming to elucidate Pin1's promise as a potential anticancer agent, particularly in the context of pancreatic cancer.

Nuclear PKM2 binds pre-mRNA at folded G-quadruplexes and reveals their gene regulatory role

Nuclear localization of the metabolic enzyme PKM2 is widely observed in various cancer types. We identify nuclear PKM2 as a non-canonical RNA-binding protein (RBP) that specifically interacts with folded RNA G-quadruplex (rG4) structures in precursor mRNAs (pre-mRNAs). PKM2 occupancy at rG4s prevents the binding of repressive RBPs, such as HNRNPF, and promotes the expression of rG4-containing pre-mRNAs (the "rG4ome"). We observe an upregulation of the rG4ome during epithelial-to-mesenchymal transition and a negative correlation of rG4 abundance with patient survival in different cancer types. By preventing the nuclear accumulation of PKM2, we could repress the rG4ome in triple-negative breast cancer cells and reduce migration and invasion of cancer cells in vitro and in xenograft mouse models. Our data suggest that the balance of folded and unfolded rG4s controlled by RBPs impacts gene expression during tumor progression.

Non-metabolic enzyme function of pyruvate kinase M2 in breast cancer

Breast cancer (BC) is a prevalent malignant tumor in women, and its incidence has been steadily increasing in recent years. Compared with other types of cancer, it has the highest mortality and morbidity rates in women. So, it is crucial to investigate the underlying mechanisms of BC development and identify specific therapeutic targets. Pyruvate kinase M2 (PKM2), an important metabolic enzyme in glycolysis, has been found to be highly expressed in BC. It can also move to the nucleus and interact with various transcription factors and proteins, including hypoxia-inducible factor-1α (HIF-1α), signal transducer and activator of transcription 3 (STAT3), β-catenin, cellular-myelocytomatosis oncogene (c-Myc), nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB), and mammalian sterile 20-like kinase 1 (MST1). This interaction leads to non-metabolic functions that control the cell cycle, proliferation, apoptosis, migration, invasion, angiogenesis, and tumor microenvironment in BC. This review provides an overview of the latest advancements in understanding the interactions between PKM2 and different transcription factors and proteins that influence the initiation and progression of BC. It also examined how natural drugs and noncoding RNAs affect various biological processes in BC cells through the regulation of the non-metabolic enzyme functions of PKM2. The findings provide valuable insights for improving the prognosis and developing targeted therapies for BC in the coming years.

Targeting CircAURKA prevents colorectal cancer progression via enhancing CTNNB1 protein degradation

Tumor progression of colorectal cancer (CRC) seriously affects patient prognosis. For CRC patients with advanced-stage disease, it is still necessary to continuously explore more effective targeted therapeutic drugs. Circular RNAs (circRNAs) are involved in the regulation of tumor biology. We screened circAURKA, which was significantly highly expressed in CRC by previous high-throughput RNA sequencing. In vitro experiments were performed to investigate the effect of the circRNA on the proliferation and metastasis of HCT116 and SW480 cells. In addition, we used the EdU assay, Transwell assay, nude mouse xenograft tumor model and nude mouse tail vein metastasis model to examine the effect of circAURKA on the proliferation and metastasis of CRC. Mechanistically, fluorescent in situ hybridization (FISH), RNA pull-down, RNA immunoprecipitation (RIP), protein coimmunoprecipitation (co-IP) experiments and animal models were performed to confirm the underlying mechanisms of circAURKA. CircAURKA was significantly highly expressed in CRC tissues and colorectal cells and mainly present in the cytoplasm. The circRNA promoted the proliferation and metastasis of CRC cells in vitro and in vivo. In terms of the molecular mechanism, circAURKA inhibited the degradation of the CTNNB1 protein by promoting the interaction between ACLY and the CTNNB1 protein, thereby promoting the proliferation and metastasis of CRC cells. In addition, circAURKA stability was regulated by m6A methylation modification. This study revealed that circAURKA promoted the proliferation and metastasis of CRC by inhibiting CTNNB1 protein degradation, providing a basis for the development of targeted drugs to control CRC progression.

PAK5-mediated PKM2 phosphorylation is critical for anaerobic glycolysis in endometriosis

P21-activated kinase 5 (PAK5) belongs to the PAK-II subfamily, which is an important regulator of cell survival, adhesion, and motility. However, the functions of PAK5 in endometriosis remain unclear. Here, PAK5 is strikingly upregulated in endometriosis. Furthermore, the knockdown of PAK5 or its inhibitor GNE 2861 blocks the development of endometriosis, which is equally demonstrated in PAK5-knockout mice. In addition, PAK5 promotes glycolysis by enhancing the protein stability of pyruvate kinase 2 (PKM2) in endometriotic cells, which is a key enzyme for glucose metabolism. Moreover, the phosphorylation of PKM2 at Ser519 by PAK5 mediates endometriosis cell proliferation and metastasis. Collectively, PAK5 plays an indispensable role in endometriosis. Our findings demonstrate that PAK5 is an important target for the treatment of endometriosis.

Roles of clinical application of lenvatinib and its resistance mechanism in advanced hepatocellular carcinoma (Review)

Lenvatinib (LEN) is a multi-target TKI, which plays a pivotal role in the treatment of advanced hepatocellular carcinoma (HCC). The inevitable occurrence of drug resistance still prevents curative potential and is deleterious for the prognosis, and a growing body of studies is accumulating, which have devoted themselves to unveiling its underlying resistance mechanism and made some progress. The dysregulation of crucial signaling pathways, non-coding RNA and RNA modifications were proven to be associated with LEN resistance. A range of drugs were found to influence LEN therapeutic efficacy. In addition, the superiority of LEN combination therapy has been shown to potentially overcome the limitations of LEN monotherapy in a series of research, and a range of promising indicators for predicting treatment response and prognosis have been discovered in recent years. In this review, we summarize the latest developments in LEN resistance, the efficacy and safety of LEN combination therapy as well as associated indicators, which may provide new insight into its resistance as well as ideas in the treatment of advanced HCC.

Network medicine based approach for identifying the type 2 diabetes, osteoarthritis and triple negative breast cancer interactome: Finding the hub of hub genes

The increasing prevalence of multi-morbidities, particularly the incidence of breast cancer in diabetic/osteoarthritic patients emphasize on the need for exploring the underlying molecular mechanisms resulting in carcinogenesis. To address this, present study employed a systems biology approach to identify switch genes pivotal to the crosstalk between diseased states resulting in multi-morbid conditions. Hub genes previously reported for type 2 diabetes mellitus (T2DM), osteoarthritis (OA), and triple negative breast cancer (TNBC), were extracted from published literature and fed into an integrated bioinformatics analyses pipeline. Thirty-one hub genes common to all three diseases were identified. Functional enrichment analyses showed these were mainly enriched for immune and metabolism associated terms including advanced glycation end products (AGE) pathways, cancer pathways, particularly breast neoplasm, immune system signalling and adipose tissue. The T2DM-OA-TNBC interactome was subjected to protein-protein interaction network analyses to identify meta hub/clustered genes. These were prioritized and wired into a three disease signalling map presenting the enriched molecular crosstalk on T2DM-OA-TNBC axes to gain insight into the molecular mechanisms underlying disease-disease interactions. Deciphering the molecular bases for the intertwined metabolic and immune states may potentiate the discovery of biomarkers critical for identifying and targeting the immuno-metabolic origin of disease.

Agonist Discovery for Membrane Proteins on Live Cells by Using DNA-encoded Libraries

Identifying biologically active ligands for membrane proteins is an important task in chemical biology. We report an approach to directly identify small molecule agonists against membrane proteins by selecting DNA-encoded libraries (DELs) on live cells. This method connects extracellular ligand binding with intracellular biochemical transformation, thereby biasing the selection toward agonist identification. We have demonstrated the methodology with three membrane proteins: epidermal growth factor receptor (EGFR), thrombopoietin receptor (TPOR), and insulin receptor (INSR). A ∼30 million and a 1.033 billion-compound DEL were selected against these targets, and novel agonists with subnanomolar affinity and low micromolar cellular activities have been discovered. The INSR agonists activated the receptor by possibly binding to an allosteric site, exhibited clear synergistic effects with insulin, and activated the downstream signaling pathways. Notably, the agonists did not activate the insulin-like growth factor 1 receptor (IGF-1R), a highly homologous receptor whose activation may lead to tumor progression. Collectively, this work has developed an approach toward "functional" DEL selections on the cell surface and may provide a widely applicable method for agonist discovery for membrane proteins.

Urinary PKM2, a marker predicating acute kidney injury in patients with sepsis

PURPOSE

Acute kidney injury (AKI) is a complication commonly occurred in patients with sepsis, and AKI has become the leading cause associated with mortality. PKM2, as a rate-limiting enzyme of glycolysis, was considered to be involved in AKI in vitro and animal models. However, there have been no studies reported on the expression of PKM2 in humans and its association with AKI.

METHODS

A retrospective study including 57 patients (35 males and 22 females) that were admitted into hospital in 2019 was carried out in our research. The basic characteristics and clinical parameters of each patient were collected from patients' medical records. We assessed changes in the expression of serum and urinary PKM2 using ELISA and its association with clinical manifestations in patients with sepsis through correlation analysis. Besides, ROC analysis was applied for evaluating the role of PKM2 in predicting AKI and death rate.

RESULTS

Urinary PKM2 is obviously increased in patients with sepsis-associated AKI (P < 0.05), while no significant change was found in the expression of serum PKM2. Moreover, the expression of urinary PKM2 is positively correlated with serum creatinine (r=0.577, P < 0.01) and blood-urea-nitrogen (r=0.531, P<0.01). In addition, it is negatively correlated with glomerular filtration rate (r=-0.583, P<0.01). Besides, ROC analysis indicated that urinary PKM2 could be a predictor of AKI in patients with sepsis (AUC-ROC, 0.819; SE, 0.086, P = 0.004, 95% CI 0.651-0.986).

CONCLUSIONS

Urinary PKM2 could be a marker predicting acute kidney injury in patients with sepsis.

Metformin Suppresses Both PD-L1 Expression in Cancer Cells and Cancer-Induced PD-1 Expression in Immune Cells to Promote Antitumor Immunity

Background

Metformin, a drug prescribed for patients with type 2 diabetes, has potential efficacy in enhancing antitumor immunity; however, the detailed underlying mechanisms remain to be elucidated. Therefore, we aimed to identify the inhibitory molecular mechanisms of metformin on programmed death ligand 1 (PD-L1) expression in cancer cells and programmed death 1 (PD-1) expression in immune cells.

Methods

We employed a luciferase reporter assay, quantitative real-time PCR, immunoblotting analysis, immunoprecipitation and ubiquitylation assays, and a natural killer (NK) cell-mediated tumor cell cytotoxicity assay. A mouse xenograft tumor model was used to evaluate the effect of metformin on tumor growth, followed by flow-cytometric analysis using tumor-derived single-cell suspensions.

Results

Metformin decreased AKT-mediated β-catenin S552 phosphorylation and subsequent β-catenin transactivation in an adenosine monophosphate-activated protein kinase (AMPK) activation-dependent manner, resulting in reduced CD274 (encoding PD-L1) transcription in cancer cells. Tumor-derived soluble factors enhanced PD-1 protein stability in NK and T cells via dissociation of PD-1 from ubiquitin E3 ligases and reducing PD-1 polyubiquitylation. Metformin inhibited the tumor-derived soluble factor-reduced binding of PD-1 to E3 ligases and PD-1 polyubiquitylation, resulting in PD-1 protein downregulation in an AMPK activation-dependent manner. These inhibitory effects of metformin on both PD-L1 and PD-1 expression ameliorated cancer-reduced cytotoxic activity of immune cells in vitro and decreased tumor immune evasion and growth in vivo.

Conclusions

Metformin blocks both PD-L1 and PD-1 within the tumor microenvironment. This study provided a mechanistic insight into the efficacy of metformin in improving immunotherapy in human cancer.

Function of a complex of p-Y42 RhoA GTPase and pyruvate kinase M2 in EGF signaling pathway in glioma cells

Epidermal growth factor (EGF) is known to be a critical stimulant for inducing the proliferation of glioma cancer cells. In our study, we observed that GST-RhoA binds to pyruvate kinase M2 (PKM2) in vitro. While EGF reduced the levels of RhoA protein, it significantly increased p-Y42 RhoA, as well as PKM1 and PKM2 in LN18 glioma cell line. We determined that RhoA undergoes degradation through ubiquitination involving SCF1 and Smurf1. Interestingly, we observed that p-Y42 RhoA binds to PKM2, while the dephosphomimetic form, RhoA Y42F, did not. Additionally, our observation revealed that PKM2 stabilized both RhoA and p-Y42 RhoA. Importantly, RhoA, p-Y42 RhoA, and PKM2, but not RhoA-GTP, were localized in the nucleus upon EGF stimulation. Knockdown of RhoA with siRNA resulted in the reduced levels of phosphoglycerate kinase1 (PGK1) and microtubule affinity-regulating kinase 4 (MARK). Furthermore, we found that the promoter of PGK1 was associated with β-catenin and YAP. Notably, p-Y42 RhoA and PKM2 co-immunoprecipitated with β-catenin and YAP. Based on these findings, we proposed a novel mechanism by which p-Y42 RhoA and PKM2, in conjunction with β-catenin and YAP, regulate PGK1 expression, contributing to the progression of glioma upon EGF.

Postsynaptic lncRNA Sera/Pkm2 pathway orchestrates the transition from social competition to rank by remodeling the neural ensemble in mPFC

Individuals' continuous success in competitive interactions with conspecifics strongly affects their social hierarchy. Medial prefrontal cortex (mPFC) is the key brain region mediating both social competition and hierarchy. However, the molecular regulatory mechanisms underlying the neural ensemble in the mPFC remains unclear. Here, we demonstrate that in excitatory neurons of prelimbic cortex (PL), lncRNA Sera remodels the utilization of Pkm Exon9 and Exon10, resulting in a decrease in the Pkm1/2 ratio in highly competitive mice. By employing a tet-on/off system, we disrupt or rebuild the normal Pkm1/2 ratio by controlling the expression of Pkm2 in PL excitatory neurons. We find that long-term Pkm2 modulation induces timely competition alteration and hysteretic rank change, through phosphorylating the Ser845 site of GluA1. Together, this study uncovers a crucial role of lncRNA Sera/Pkm2 pathway in the transition of social competition to rank by remodeling neural ensemble in mPFC.

Polyphyllin II Induces Apoptosis in Fibrosarcoma Cells via Activating Pyruvate Kinase M2

Aerobic glycolysis is a metabolic reprogramming of tumor cells that is essential for sustaining their phenotype of fast multiplication by continuously supplying energy and mass. Pyruvate kinase M2 (PKM2) has a vital role in this process, which has given it high interest as a target for anticancer drug development. With potent toxicity to many types of cancer cells, polyphyllin II (PP2), a steroidal saponin isolated from the herbaceous plant Rhizoma paridis, brought to our attention that it might interfere with the PKM2 activity. In this study, we discovered that PP2 was a novel agonist of PKM2. PP2 activated recombinant PKM2 and changed the protein's oligomeric state to activate intracellular PKM2. At the same time, PP2 suppressed its protein kinase function by decreasing the content of nuclear PKM2. The mRNA levels of its downstream genes, such as Glut1, LDHA, and MYC, were inhibited. In addition, PP2 induced oxidative stress by downregulating the expression and activity of antioxidant proteins such as NQO1, TrxR, and Trx in HT-1080 cells, which in turn led to mitochondrial dysfunction and ultimately induced apoptosis. Moreover, PP2 reduced the proliferation and migration of HT-1080 cells. Thus, targeting the glycolysis pathway offers an unprecedented mode of action for comprehending PP2's pharmacological impacts and advances PP2's further development in fibrosarcoma therapy.

SHP2 mutations promote glycolysis and inhibit apoptosis via PKM2/hnRNPK signaling in colorectal cancer

Colorectal cancer (CRC) is one of the most common gastrointestinal tumors. Src homology-2 domain-containing protein tyrosine phosphatase-2 (SHP2) mutations occur in human solid tumors, including CRC. However, the function and underlying mechanism in CRC have not been well characterized. We demonstrated that the SHP2D61Y and SHP2E76K mutations occurred in CRC tissues, and these mutations promoted CRC cell proliferation, migration/invasion, and reduced CDDP-induced cell apoptosis in vitro and in vivo. Mechanistically, SHP2D61Y and SHP2E76K promote glycolysis by accelerating pyruvate kinase M2 (PKM2) nuclear translocation through mechanism beyond ERK activation. PKM2-IN-1 attenuates PKM2-dependent glycolysis and reduce glucose uptake, lactate production, and ATP levels promoted by SHP2D61Y and SHP2E76K in CRC cells. Furthermore, PKM2 upregulates heterogeneous nuclear ribonucleoprotein K (hnRNPK) expression and increases CRC cell proliferation and migration/invasion via regulating hnRNPK ubiquitination. These findings provide evidence that SHP2D61Y and SHP2E76K regulate CDDP-induced apoptosis, glucose metabolism, and CRC migration/invasion through PKM2 nuclear translocation and PKM2/hnRNPK signaling.

Disintegration of Cav-1/β-catenin complex attenuates neuronal death after ischemia-reperfusion injury by promoting β-catenin nuclear translocation

BACKGROUND

The roles of Caveolin-1 (Cav-1) and the Wnt/β-catenin signaling pathways in cerebral ischemia-reperfusion (I/R) injury are well established. The translocation of β-catenin into the nucleus is critical for regulating neuronal apoptosis, repair, and neurogenesis within the ischemic brain. It has been reported that the scaffold domain of Caveolin-1 (Cav-1) (residues 95-98) interacts with β-catenin (residues 330-337). However, the specific contribution of the Cav-1/β-catenin complex to I/R injury remains unknown.

METHODS AND RESULTS

To investigate the mechanism underlying the involvement of the Cav-1/β-catenin complex in the subcellular translocation of β-catenin and its subsequent effects on cerebral I/R injury, we treated ischemic brains with ASON (Cav-1 antisense oligodeoxynucleotides) or FTVT (a competitive peptide antagonist of the Cav-1 and β-catenin interaction). Our study demonstrated that the binding of Cav-1 to β-catenin following I/R injury prevented the nuclear accumulation of β-catenin. Treatment with ASON or FTVT after I/R injury significantly increased the levels of nuclear β-catenin. Furthermore, ASON reduced the phosphorylation of β-catenin at Ser33, Ser37, and Thr41, which contributes to its proteasomal degradation, while FTVT increased phosphorylation at Tyr333, which is associated with its nuclear translocation.

CONCLUSIONS

The above results indicate that the formation of the Cav-1/β-catenin complex anchors β-catenin in the cytoplasm following I/R injury. Additionally, both ASON and FTVT treatments attenuated neuronal death in ischemic brains. Our study suggests that targeting the interaction between Cav-1 and β-catenin serve as a novel therapeutic strategy to protect against neuronal damage during cerebral injury.

Chrysophanol inhibits of colorectal cancer cell motility and energy metabolism by targeting the KITENIN/ErbB4 oncogenic complex

BACKGROUND

Expression of the KITENIN/ErbB4 oncogenic complex is associated with metastasis of colorectal cancer to distant organs and lymph nodes and is linked with poor prognosis and poor survival.

METHODS

Here, we used in vitro and in silico methods to test the ability of chrysophanol, a molecule of natural origin, to suppress the progression of colorectal cancer by targeting the KITENIN/ErbB4 complex.

RESULTS

Chrysophanol binds to ErbB4, disrupting the ErbB4/KITENIN complex and causing autophagic degradation of KITENIN. We demonstrated that chrysophanol binds to ErbB4 according to a molecular docking model. Chrysophanol reversed KITENIN-mediated effects on cell motility, aerobic glycolysis, and expression of downstream effector genes. Moreover, under conditions of KITENIN overexpression, chrysophanol suppressed the production of onco-metabolites.

CONCLUSION

Chrysophanol suppresses oncogenic activities by targeting the KITENIN/ErbB4 complex.

Arsenic activated GLUT1-mTORC1/HIF-1α-PKM2 positive feedback networks promote proliferation and migration of bladder epithelial cells

Arsenic (As) is recognized as a potent environmental contaminant associated with bladder carcinogenesis. However, its molecular mechanism remains unclear. Metabolic reprogramming is one of the hallmarks of cancer and is as a central feature of malignancy. Here, we performed the study of cross-talk between the mammalian target of rapamycin complex 1 (mTORC1)/ Hypoxia-inducible factor 1 alpha (HIF-1α) pathway and aerobic glycolysis in promoting the proliferation and migration of bladder epithelial cells treated by arsenic in vivo and in vitro. We demonstrated that arsenite promoted N-methyl-N-nitrosourea (MNU)-induced tumor formation in the bladder of rats and the malignant behavior of human ureteral epithelial (SV-HUC-1) cell. We found that arsenite positively regulated the mTORC1/HIF-1α pathway through glucose transporter protein 1 (GLUT1), which involved in the malignant progression of bladder epithelial cells relying on glycolysis. In addition, pyruvate kinase M2 (PKM2) increased by arsenite reduced the protein expressions of succinate dehydrogenase (SDH) and fumarate hydratase (FH), leading to the accumulation of tumor metabolites of succinate and fumarate. Moreover, heat shock protein (HSP)90, functioning as a chaperone protein, stabilized PKM2 and thereby regulated the proliferation and aerobic glycolysis in arsenite treated SV-HUC-1 cells. Taken together, these results provide new insights into mTORC1/HIF-1α and PKM2 networks as critical molecular targets that contribute to the arsenic-induced malignant progression of bladder epithelial cells.

The regulatory roles and clinical significance of glycolysis in tumor

Metabolic reprogramming has been demonstrated to have a significant impact on the biological behaviors of tumor cells, among which glycolysis is an important form. Recent research has revealed that the heightened glycolysis levels, the abnormal expression of glycolytic enzymes, and the accumulation of glycolytic products could regulate the growth, proliferation, invasion, and metastasis of tumor cells and provide a favorable microenvironment for tumor development and progression. Based on the distinctive glycolytic characteristics of tumor cells, novel imaging tests have been developed to evaluate tumor proliferation and metastasis. In addition, glycolytic enzymes have been found to serve as promising biomarkers in tumor, which could provide assistance in the early diagnosis and prognostic assessment of tumor patients. Numerous glycolytic enzymes have been identified as potential therapeutic targets for tumor treatment, and various small molecule inhibitors targeting glycolytic enzymes have been developed to inhibit tumor development and some of them are already applied in the clinic. In this review, we systematically summarized recent advances of the regulatory roles of glycolysis in tumor progression and highlighted the potential clinical significance of glycolytic enzymes and products as novel biomarkers and therapeutic targets in tumor treatment.

ACLY alternative splicing correlates with cancer phenotypes

ATP-citrate lyase (ACLY) links carbohydrate and lipid metabolism and provides nucleocytosolic acetyl-CoA for protein acetylation. ACLY has two major splice isoforms: the full-length canonical "long" isoform and an uncharacterized "short" isoform in which exon 14 is spliced out. Exon 14 encodes 10 amino acids within an intrinsically disordered region and includes at least one dynamically phosphorylated residue. Both isoforms are expressed in healthy tissues to varying degrees. Analysis of human transcriptomic data revealed that the percent spliced in (PSI) of exon 14 is increased in several cancers and correlated with poorer overall survival in a pan-cancer analysis, though not in individual tumor types. This prompted us to explore potential biochemical and functional differences between ACLY isoforms. Here, we show that there are no discernible differences in enzymatic activity or stability between isoforms or phosphomutants of ACLY in vitro. Similarly, both isoforms and phosphomutants were able to rescue ACLY functions, including fatty acid synthesis and bulk histone acetylation, when re-expressed in Acly knockout cells. Deletion of Acly exon 14 in mice did not overtly impact development or metabolic physiology nor did it attenuate tumor burden in a genetic model of intestinal cancer. Notably, expression of epithelial splicing regulatory protein 1 (ESRP1) is highly correlated with ACLY PSI. We report that ACLY splicing is regulated by ESRP1. In turn, both ESRP1 expression and ACLY PSI are correlated with specific immune signatures in tumors. Despite these intriguing patterns of ACLY splicing in healthy and cancer tissues, functional differences between the isoforms remain elusive.

Lipid metabolism dynamics in cancer stem cells: potential targets for cancers

Cancer stem cells (CSCs) represent a small subset of heterogeneous cells within tumors that possess the ability to self-renew and initiate tumorigenesis. They serve as potential drivers for tumor initiation, metastasis, recurrence, and drug resistance. Recent research has demonstrated that the stemness preservation of CSCs is heavily reliant on their unique lipid metabolism alterations, enabling them to maintain their own environmental homeostasis through various mechanisms. The primary objectives involve augmenting intracellular fatty acid (FA) content to bolster energy supply, promoting β-oxidation of FA to optimize energy utilization, and elevating the mevalonate (MVA) pathway for efficient cholesterol synthesis. Additionally, lipid droplets (LDs) can serve as alternative energy sources in the presence of glycolysis blockade in CSCs, thereby safeguarding FA from peroxidation. Furthermore, the interplay between autophagy and lipid metabolism facilitates rapid adaptation of CSCs to the harsh microenvironment induced by chemotherapy. In this review, we comprehensively review recent studies pertaining to lipid metabolism in CSCs and provide a concise overview of the indispensable role played by LDs, FA, cholesterol metabolism, and autophagy in maintaining the stemness of CSCs.

Muscle-specific pyruvate kinase isoforms, PKM1 and PKM2, regulate mammalian SWI/SNF proteins and histone 3 phosphorylation during myoblast differentiation

Pyruvate kinase is a glycolytic enzyme that converts phosphoenolpyruvate and ADP into pyruvate and ATP. There are two genes that encode pyruvate kinase in vertebrates; Pkm and Pkl encode muscle- and liver/erythrocyte-specific forms, respectively. Each gene encodes two isoenzymes due to alternative splicing. Both muscle-specific enzymes, PKM1 and PKM2, function in glycolysis, but PKM2 also has been implicated in gene regulation due to its ability to phosphorylate histone 3 threonine 11 (H3T11) in cancer cells. Here, we examined the roles of PKM1 and PKM2 during myoblast differentiation. RNA-seq analysis revealed that PKM2 promotes the expression of Dpf2/Baf45d and Baf250a/Arid1A. DPF2 and BAF250a are subunits that identify a specific sub-family of the mammalian SWI/SNF (mSWI/SNF) of chromatin remodeling enzymes that is required for the activation of myogenic gene expression during differentiation. PKM2 also mediated the incorporation of DPF2 and BAF250a into the regulatory sequences controlling myogenic gene expression. PKM1 did not affect expression but was required for nuclear localization of DPF2. Additionally, PKM2 was required not only for the incorporation of phosphorylated H3T11 in myogenic promoters but also for the incorporation of phosphorylated H3T6 and H3T45 at myogenic promoters via regulation of AKT and protein kinase C isoforms that phosphorylate those amino acids. Our results identify multiple unique roles for PKM2 and a novel function for PKM1 in gene expression and chromatin regulation during myoblast differentiation.

Glycolysis in the tumor microenvironment: a driver of cancer progression and a promising therapeutic target

Even with sufficient oxygen, tumor cells use glycolysis to obtain the energy and macromolecules they require to multiply, once thought to be a characteristic of tumor cells known as the "Warburg effect". In fact, throughout the process of carcinogenesis, immune cells and stromal cells, two major cellular constituents of the tumor microenvironment (TME), also undergo thorough metabolic reprogramming, which is typified by increased glycolysis. In this review, we provide a full-scale review of the glycolytic remodeling of several types of TME cells and show how these TME cells behave in the acidic milieu created by glucose shortage and lactate accumulation as a result of increased tumor glycolysis. Notably, we provide an overview of putative targets and inhibitors of glycolysis along with the viability of using glycolysis inhibitors in combination with immunotherapy and chemotherapy. Understanding the glycolytic situations in diverse cells within the tumor immunological milieu will aid in the creation of subsequent treatment plans.

MYG1 drives glycolysis and colorectal cancer development through nuclear-mitochondrial collaboration

Metabolic remodeling is a strategy for tumor survival under stress. However, the molecular mechanisms during the metabolic remodeling of colorectal cancer (CRC) remain unclear. Melanocyte proliferating gene 1 (MYG1) is a 3'-5' RNA exonuclease and plays a key role in mitochondrial functions. Here, we uncover that MYG1 expression is upregulated in CRC progression and highly expressed MYG1 promotes glycolysis and CRC progression independent of its exonuclease activity. Mechanistically, nuclear MYG1 recruits HSP90/GSK3β complex to promote PKM2 phosphorylation, increasing its stability. PKM2 transcriptionally activates MYC and promotes MYC-medicated glycolysis. Conversely, c-Myc also transcriptionally upregulates MYG1, driving the progression of CRC. Meanwhile, mitochondrial MYG1 on the one hand inhibits oxidative phosphorylation (OXPHOS), and on the other hand blocks the release of Cyt c from mitochondria and inhibits cell apoptosis. Clinically, patients with KRAS mutation show high expression of MYG1, indicating a high level of glycolysis and a poor prognosis. Targeting MYG1 may disturb metabolic balance of CRC and serve as a potential target for the diagnosis and treatment of CRC.

Pyruvate kinase M2 sustains cardiac mitochondrial quality surveillance in septic cardiomyopathy by regulating prohibitin 2 abundance via S91 phosphorylation

The endogenous mitochondrial quality control (MQC) system serves to protect mitochondria against cellular stressors. Although mitochondrial dysfunction contributes to cardiac damage during many pathological conditions, the regulatory signals influencing MQC disruption during septic cardiomyopathy (SC) remain unclear. This study aimed to investigate the involvement of pyruvate kinase M2 (PKM2) and prohibitin 2 (PHB2) interaction followed by MQC impairment in the pathogenesis of SC. We utilized LPS-induced SC models in PKM2 transgenic (PKM2TG) mice, PHB2S91D-knockin mice, and PKM2-overexpressing HL-1 cardiomyocytes. After LPS-induced SC, cardiac PKM2 expression was significantly downregulated in wild-type mice, whereas PKM2 overexpression in vivo sustained heart function, suppressed myocardial inflammation, and attenuated cardiomyocyte death. PKM2 overexpression relieved sepsis-related mitochondrial damage via MQC normalization, evidenced by balanced mitochondrial fission/fusion, activated mitophagy, restored mitochondrial biogenesis, and inhibited mitochondrial unfolded protein response. Docking simulations, co-IP, and domain deletion mutant protein transfection experiments showed that PKM2 phosphorylates PHB2 at Ser91, preventing LPS-mediated PHB2 degradation. Additionally, the A domain of PKM2 and the PHB domain of PHB2 are required for PKM2-PHB2 binding and PHB2 phosphorylation. After LPS exposure, expression of a phosphorylation-defective PHB2S91A mutant negated the protective effects of PKM2 overexpression. Moreover, knockin mice expressing a phosphorylation-mimetic PHB2S91D mutant showed improved heart function, reduced inflammation, and preserved mitochondrial function following sepsis induction. Abundant PKM2 expression is a prerequisite to sustain PKM2-PHB2 interaction which is a key element for preservation of PHB2 phosphorylation and MQC, presenting novel interventive targets for the treatment of septic cardiomyopathy.

Dux activates metabolism-lactylation-MET network during early iPSC reprogramming with Brg1 as the histone lactylation reader

The process of induced pluripotent stem cells (iPSCs) reprogramming involves several crucial events, including the mesenchymal-epithelial transition (MET), activation of pluripotent genes, metabolic reprogramming, and epigenetic rewiring. Although these events intricately interact and influence each other, the specific element that regulates the reprogramming network remains unclear. Dux, a factor known to promote totipotency during the transition from embryonic stem cells (ESC) to 2C-like ESC (2CLC), has not been extensively studied in the context of iPSC reprogramming. In this study, we demonstrate that the modification of H3K18la induced by Dux overexpression controls the metabolism-H3K18la-MET network, enhancing the efficiency of iPSC reprogramming through a metabolic switch and the recruitment of p300 via its C-terminal domain. Furthermore, our proteomic analysis of H3K18la immunoprecipitation experiment uncovers the specific recruitment of Brg1 during reprogramming, with both H3K18la and Brg1 being enriched on the promoters of genes associated with pluripotency and epithelial junction. In summary, our study has demonstrated the significant role of Dux-induced H3K18la in the early reprogramming process, highlighting its function as a potent trigger. Additionally, our research has revealed, for the first time, the binding of Brg1 to H3K18la, indicating its role as a reader of histone lactylation.

Specific regulation of epigenome landscape by metabolic enzymes and metabolites

Metabolism includes anabolism and catabolism, which play an essential role in many biological processes. Chromatin modifications are post-translational modifications of histones and nucleic acids that play important roles in regulating chromatin-associated processes such as gene transcription. There is a tight connection between metabolism and chromatin modifications. Many metabolic enzymes and metabolites coordinate cellular activities with alterations in nutrient availability by regulating gene expression through epigenetic mechanisms such as DNA methylation and histone modifications. The dysregulation of gene expression by metabolism and epigenetic modifications may lead to diseases such as diabetes and cancer. Recent studies reveal that metabolic enzymes and metabolites specifically regulate chromatin modifications, including modification types, modification residues and chromatin regions. This specific regulation has been implicated in the development of human diseases, yet the underlying mechanisms are only beginning to be uncovered. In this review, we summarise recent studies of the molecular mechanisms underlying the metabolic regulation of histone and DNA modifications and discuss how they contribute to pathogenesis. We also describe recent developments in technologies used to address the key questions in this field. We hope this will inspire further in-depth investigations of the specific regulatory mechanisms involved, and most importantly will shed lights on the development of more effective disease therapies.

Glycolytic enzyme PFKL governs lipolysis by promoting lipid droplet-mitochondria tethering to enhance β-oxidation and tumor cell proliferation

Lipid droplet tethering with mitochondria for fatty acid oxidation is critical for tumor cells to counteract energy stress. However, the underlying mechanism remains unclear. Here, we demonstrate that glucose deprivation induces phosphorylation of the glycolytic enzyme phosphofructokinase, liver type (PFKL), reducing its activity and favoring its interaction with perilipin 2 (PLIN2). On lipid droplets, PFKL acts as a protein kinase and phosphorylates PLIN2 to promote the binding of PLIN2 to carnitine palmitoyltransferase 1A (CPT1A). This results in the tethering of lipid droplets and mitochondria and the recruitment of adipose triglyceride lipase to the lipid droplet-mitochondria tethering regions to engage lipid mobilization. Interfering with this cascade inhibits tumor cell proliferation, promotes apoptosis and blunts liver tumor growth in male mice. These results reveal that energy stress confers a moonlight function to PFKL as a protein kinase to tether lipid droplets with mitochondria and highlight the crucial role of PFKL in the integrated regulation of glycolysis, lipid metabolism and mitochondrial oxidation.

PKM2 functions as a histidine kinase to phosphorylate PGAM1 and increase glycolysis shunts in cancer

Phosphoglycerate mutase 1 (PGAM1) is a key node enzyme that diverts the metabolic reactions from glycolysis into its shunts to support macromolecule biosynthesis for rapid and sustainable cell proliferation. It is prevalent that PGAM1 activity is upregulated in various tumors; however, the underlying mechanism remains unclear. Here, we unveil that pyruvate kinase M2 (PKM2) moonlights as a histidine kinase in a phosphoenolpyruvate (PEP)-dependent manner to catalyze PGAM1 H11 phosphorylation, that is essential for PGAM1 activity. Moreover, monomeric and dimeric but not tetrameric PKM2 are efficient to phosphorylate and activate PGAM1. In response to epidermal growth factor signaling, Src-catalyzed PGAM1 Y119 phosphorylation is a prerequisite for PKM2 binding and the subsequent PGAM1 H11 phosphorylation, which constitutes a discrepancy between tumor and normal cells. A PGAM1-derived pY119-containing cell-permeable peptide or Y119 mutation disrupts the interaction of PGAM1 with PKM2 and PGAM1 H11 phosphorylation, dampening the glycolysis shunts and tumor growth. Together, these results identify a function of PKM2 as a histidine kinase, and illustrate the importance of enzyme crosstalk as a regulatory mode during metabolic reprogramming and tumorigenesis.

The emerging importance of the α-keto acid dehydrogenase complexes in serving as intracellular and intercellular signaling platforms for the regulation of metabolism

The α-keto acid dehydrogenase complex (KDHc) class of mitochondrial enzymes is composed of four members: pyruvate dehydrogenase (PDHc), α-ketoglutarate dehydrogenase (KGDHc), branched-chain keto acid dehydrogenase (BCKDHc), and 2-oxoadipate dehydrogenase (OADHc). These enzyme complexes occupy critical metabolic intersections that connect monosaccharide, amino acid, and fatty acid metabolism to Krebs cycle flux and oxidative phosphorylation (OxPhos). This feature also imbues KDHc enzymes with the heightened capacity to serve as platforms for propagation of intracellular and intercellular signaling. KDHc enzymes serve as a source and sink for mitochondrial hydrogen peroxide (mtH2O2), a vital second messenger used to trigger oxidative eustress pathways. Notably, deactivation of KDHc enzymes through reversible oxidation by mtH2O2 and other electrophiles modulates the availability of several Krebs cycle intermediates and related metabolites which serve as powerful intracellular and intercellular messengers. The KDHc enzymes also play important roles in the modulation of mitochondrial metabolism and epigenetic programming in the nucleus through the provision of various acyl-CoAs, which are used to acylate proteinaceous lysine residues. Intriguingly, nucleosomal control by acylation is also achieved through PDHc and KGDHc localization to the nuclear lumen. In this review, I discuss emerging concepts in the signaling roles fulfilled by the KDHc complexes. I highlight their vital function in serving as mitochondrial redox sensors and how this function can be used by cells to regulate the availability of critical metabolites required in cell signaling. Coupled with this, I describe in detail how defects in KDHc function can cause disease states through the disruption of cell redox homeodynamics and the deregulation of metabolic signaling. Finally, I propose that the intracellular and intercellular signaling functions of the KDHc enzymes are controlled through the reversible redox modification of the vicinal lipoic acid thiols in the E2 subunit of the complexes.

Imbalance in Glucose Metabolism Regulates the Transition of Microglia from Homeostasis to Disease-Associated Microglia Stage 1

Microglia undergo two-stage activation in neurodegenerative diseases, known as disease-associated microglia (DAM). TREM2 mediates the DAM2 stage transition, but what regulates the first DAM1 stage transition is unknown. We report that glucose dyshomeostasis inhibits DAM1 activation and PKM2 plays a role. As in tumors, PKM2 was aberrantly elevated in both male and female human AD brains, but unlike in tumors, it is expressed as active tetramers, as well as among TREM2+ microglia surrounding plaques in 5XFAD male and female mice. snRNAseq analyses of microglia without Pkm2 in 5XFAD mice revealed significant increases in DAM1 markers in a distinct metabolic cluster, which is enriched in genes for glucose metabolism, DAM1, and AD risk. 5XFAD mice incidentally exhibited a significant reduction in amyloid pathology without microglial Pkm2 Surprisingly, microglia in 5XFAD without Pkm2 exhibited increases in glycolysis and spare respiratory capacity, which correlated with restoration of mitochondrial cristae alterations. In addition, in situ spatial metabolomics of plaque-bearing microglia revealed an increase in respiratory activity. These results together suggest that it is not only glycolytic but also respiratory inputs that are critical to the development of DAM signatures in 5XFAD mice.

Glycolysis, a driving force of rheumatoid arthritis

Resident synoviocytes and synovial microvasculature, together with immune cells from circulation, contribute to pannus formation, the main pathological feature of rheumatoid arthritis (RA), leading to destruction of adjacent cartilage and bone. Seeds, fibroblast-like synoviocytes (FLSs), macrophages, dendritic cells (DCs), B cells, T cells and endothelial cells (ECs) seeds with high metabolic demands undergo metabolic reprogramming from oxidative phosphorylation to glycolysis in response to poor soil of RA synovium with hypoxia, nutrient deficiency and inflammatory stimuli. Glycolysis provides rapid energy supply and biosynthetic precursors to support pathogenic growth of these seeds. The metabolite lactate accumulated during this process in turn condition the soil microenvironment and affect seeds growth by modulating signalling pathways and directing lactylation modifications. This review explores in depth the survival mechanism of seeds with high metabolic demands in the poor soil of RA synovium, providing useful support for elucidating the etiology of RA. In addition, we discuss the role and major post-translational modifications of proteins and enzymes linked to glycolysis to inspire the discovery of novel anti-rheumatic targets.

Modulation of PKM2 inhibits follicular helper T cell differentiation and ameliorates inflammation in lupus-prone mice

OBJECTIVES

Expansion of follicular helper T (Tfh) cells and abnormal glucose metabolism are present in patients with systemic lupus erythematosus (SLE). Pyruvate kinase M2 (PKM2) is one of the key glycolytic enzymes, and the underlying mechanism of PKM2-mediated Tfh cell glycolysis in SLE pathogenesis remains elusive.

METHODS

We analyzed the percentage of Tfh cells and glycolysis in CD4+ T cells from SLE patients and healthy donors and performed RNA sequencing analysis of peripheral blood CD4+ T cells and differentiated Tfh cells from SLE patients. Following Tfh cell development in vitro and following treatment with PKM2 activator TEPP-46, PKM2 expression, glycolysis, and signaling pathway proteins were analyzed. Finally, diseased MRL/lpr mice were treated with TEPP-46 and assessed for treatment effects.

RESULTS

We found that Tfh cell percentage and glycolysis levels were increased in SLE patients and MRL/lpr mice. TEPP-46 induced PKM2 tetramerization, thereby inhibiting Tfh cell glycolysis levels. On the one hand, TEPP-46 reduced the dimeric PKM2 entering the nucleus and reduced binding to the transcription factor BCL6. On the other hand, TEPP-46 inhibited the AKT/GSK-3β pathway and glycolysis during Tfh cell differentiation. Finally, we confirmed that TEPP-46 effectively alleviated inflammatory damage in lupus-prone mice and reduced the expansion of Tfh cells in vivo.

CONCLUSIONS

Our results demonstrate the involvement of PKM2-mediated glycolysis in Tfh cell differentiation and SLE pathogenesis, and PKM2 could be a key therapeutic target for the treatment of SLE.

Targeting PKM2 signaling cascade with salvianic acid A normalizes tumor blood vessels to facilitate chemotherapeutic drug delivery

Aberrant tumor blood vessels are prone to propel the malignant progression of tumors, and targeting abnormal metabolism of tumor endothelial cells emerges as a promising option to achieve vascular normalization and antagonize tumor progression. Herein, we demonstrated that salvianic acid A (SAA) played a pivotal role in contributing to vascular normalization in the tumor-bearing mice, thereby improving delivery and effectiveness of the chemotherapeutic agent. SAA was capable of inhibiting glycolysis and strengthening endothelial junctions in the human umbilical vein endothelial cells (HUVECs) exposed to hypoxia. Mechanistically, SAA was inclined to directly bind to the glycolytic enzyme PKM2, leading to a dramatic decrease in endothelial glycolysis. More importantly, SAA improved the endothelial integrity via activating the β-Catenin/Claudin-5 signaling axis in a PKM2-dependent manner. Our findings suggest that SAA may serve as a potent agent for inducing tumor vascular normalization.

N6-isopentenyladenosine inhibits aerobic glycolysis in glioblastoma cells by targeting PKM2 expression and activity

Glioblastoma (GBM) is a primary tumor in the central nervous system with poor prognosis. It exhibits elevated glucose uptake and lactate production. This metabolic state of aerobic glycolysis is known as the Warburg effect. N6-isopentenyladenosine (iPA), a natural cytokine modified with an isopentenyl moiety derived from the mevalonate pathway, has well-established anti-tumor activity. It inhibits cell proliferation in glioma cells, inducing cell death by apoptosis and/or necroptosis. In the present study, we found that iPA inhibits aerobic glycolysis in unmodified U87MG cells and in the same cell line engineered to over-express wild-type epidermal growth factor receptor (EGFR) or EGFR variant III (vIII), as well as in a primary GBM4 patient-derived cell line. The detection of glycolysis showed that iPA treatment suppressed ATP and lactate production. We also evaluated the response of iPA treatment in normal human astrocyte primary cells, healthy counterpart cells of the brain. Aerobic glycolysis in treated normal human astrocyte cells did not show significant changes compared to GBM cells. To determine the mechanism of iPA action on aerobic glycolysis, we investigated the expression of certain enzymes involved in this metabolic pathway. We observed that iPA reduced the expression of pyruvate kinase M2 (PKM2), which plays a key role in the regulation of aerobic glycolysis, promoting tumor cell proliferation. The reduction of PKM2 expression is a result of the inhibition of the inhibitor of nuclear factor kappa-B kinase subunit, beta/nuclear factor-kappa B pathway upon iPA treatment. In conclusion, these experimental results show that iPA may inhibit aerobic glycolysis of GBM in stabilized cell lines and primary GBM cells by targeting the expression and activity of PKM2.

Exploring the diverse role of pyruvate kinase M2 in cancer: Navigating beyond glycolysis and the Warburg effect

Pyruvate Kinase M2, a key enzyme in glycolysis, has garnered significant attention in cancer research due to its pivotal role in the metabolic reprogramming of cancer cells. Originally identified for its association with the Warburg effect, PKM2 has emerged as a multifaceted player in cancer biology. The functioning of PKM2 is intricately regulated at multiple levels, including controlling the gene expression via various transcription factors and non-coding RNAs, as well as adding post-translational modifications that confer distinct functions to the protein. Here, we explore the diverse functions of PKM2, encompassing newly emerging roles in non-glycolytic metabolic regulation, immunomodulation, inflammation, DNA repair and mRNA processing, beyond its canonical role in glycolysis. The ever-expanding list of its functions has recently grown to include roles in subcellular compartments such as the mitochondria and extracellular milieu as well, all of which make PKM2 an attractive drug target in the pursuit of therapeutics for cancer.

Advancing glioblastoma treatment by targeting metabolism

Alterations in cellular metabolism are important hallmarks of glioblastoma(GBM). Metabolic reprogramming is a critical feature as it meets the higher nutritional demand of tumor cells, including proliferation, growth, and survival. Many genes, proteins, and metabolites associated with GBM metabolism reprogramming have been found to be aberrantly expressed, which may provide potential targets for cancer treatment. Therefore, it is becoming increasingly important to explore the role of internal and external factors in metabolic regulation in order to identify more precise therapeutic targets and diagnostic markers for GBM. In this review, we define the metabolic characteristics of GBM, investigate metabolic specificities such as targetable vulnerabilities and therapeutic resistance, as well as present current efforts to target GBM metabolism to improve the standard of care.

Nuclear translocation of metabolic enzyme PKM2 participates in high glucose-promoted HCC metastasis by strengthening immunosuppressive environment

Although some cohort studies have indicated a close association between diabetes and HCC, the underlying mechanism about the contribution of diabetes to HCC progression remains largely unknown. In the study, we applied a novel HCC model in SD rat with diabetes and a series of high glucose-stimulated cell experiments to explore the effect of a high glucose environment on HCC metastasis and its relevant mechanism. Our results uncovered a novel regulatory mechanism by which nuclear translocation of metabolic enzyme PKM2 mediated high glucose-promoted HCC metastasis. Specifically, high glucose-increased PKM2 nuclear translocation downregulates chemerin expression through the redox protein TRX1, and then strengthens immunosuppressive environment to promote HCC metastasis. To the best of our knowledge, this is the first report to elucidate the great contribution of a high glucose environment to HCC metastasis from a new perspective of enhancing the immunosuppressive microenvironment. Simultaneously, this work also highlights a previously unidentified non-metabolic role of PKM2 and opens a novel avenue for cross research and intervention for individuals with HCC and comorbid diabetes.

Metabolic Roles of HIF1, c-Myc, and p53 in Glioma Cells

The metabolic reprogramming that promotes tumorigenesis in glioblastoma is induced by dynamic alterations in the hypoxic tumor microenvironment, as well as in transcriptional and signaling networks, which result in changes in global genetic expression. The signaling pathways PI3K/AKT/mTOR and RAS/RAF/MEK/ERK stimulate cell metabolism, either directly or indirectly, by modulating the transcriptional factors p53, HIF1, and c-Myc. The overexpression of HIF1 and c-Myc, master regulators of cellular metabolism, is a key contributor to the synthesis of bioenergetic molecules that mediate glioma cell transformation, proliferation, survival, migration, and invasion by modifying the transcription levels of key gene groups involved in metabolism. Meanwhile, the tumor-suppressing protein p53, which negatively regulates HIF1 and c-Myc, is often lost in glioblastoma. Alterations in this triad of transcriptional factors induce a metabolic shift in glioma cells that allows them to adapt and survive changes such as mutations, hypoxia, acidosis, the presence of reactive oxygen species, and nutrient deprivation, by modulating the activity and expression of signaling molecules, enzymes, metabolites, transporters, and regulators involved in glycolysis and glutamine metabolism, the pentose phosphate cycle, the tricarboxylic acid cycle, and oxidative phosphorylation, as well as the synthesis and degradation of fatty acids and nucleic acids. This review summarizes our current knowledge on the role of HIF1, c-Myc, and p53 in the genic regulatory network for metabolism in glioma cells, as well as potential therapeutic inhibitors of these factors.

Leech extract alleviates idiopathic pulmonary fibrosis by TGF-β1/Smad3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Leech, as a traditional Chinese medicine for the treatment of blood circulation and blood stasis, was also widely used to cure pulmonary fibrosis in China. In clinical practice, some traditional Chinese medicine preparation such as Shui Zhi Xuan Bi Hua Xian Tang and Shui Zhi Tong Luo Capsule composed of leech, could improve the clinical symptoms and pulmonary function in patients with idiopathic pulmonary fibrosis (IPF). However, the material basis of the leech in the treatment of IPF were not yet clear.

AIM OF THE STUDY

Screen out the components of leech that have the anti-pulmonary fibrosis effects, and further explore the therapeutic mechanism of the active components.

MATERIALS AND METHODS

In this study, the different molecular weight components of leech extract samples were prepared using the semi-permeable membranes with different pore sizes. The therapeutic effects of the leech extract groups with molecular weight greater than 10 KDa (>10 KDa group), between 3 KDa and 10 KDa (3-10 KDa group), and less than 3 KDa (<3 KDa group) on pulmonary fibrosis were firstly investigated by cell proliferation and cytotoxicity assay (MTT), cell wound healing assay, immunofluorescence staining (IF) and Western blot (WB) assay through the TGF-β1-induced fibroblast cell model. Then bleomycin-induced pulmonary fibrosis (BML-induced PF) mouse model was constructed to investigate the pharmacological activities of the active component group of leech extract in vivo. Pathological changes of the mouse lung were observed by hematoxylin-eosin staining (H&E) and Masson's trichrome staining (Masson). The hydroxyproline (HYP) content of lung tissues was quantified by HYP detection kit. The levels of extracellular matrix-related fibronectin (FN) and collagen type Ⅰ (Collagen Ⅰ), pyruvate kinase M2 (PKM2) monomer and Smad7 protein were determined via WB method. PKM2 and Smad7 protein were further characterized by IF assays.

RESULTS

Using TGF-β1-induced HFL1 cell line as a PF cell model, the in vitro results demonstrated that the >10 KDa group could significantly inhibited the cell proliferation and migration, downregulated the expression level of cytoskeletal protein vimentin and α-smooth muscle actin (α-SMA), and reduced the deposition of FN and Collagen Ⅰ. In the BML-induced PF mouse model, the >10 KDa group significantly reduced the content of HYP, downregulated the expression levels of FN and Collagen Ⅰ in lung tissues, and delayed the pathological changes of lung tissue structure. The results of WB and IF assays further indicated that the >10 KDa group could up-regulate the expression level of PKM2 monomer and Smad7 protein in the cellular level, thereby delaying the progression of pulmonary fibrosis.

CONCLUSIONS

Our study revealed that the >10 KDa group was the main material basis of the leech extract that inhibited pulmonary fibrosis through TGF-β1/Smad3 signaling pathway.

Muscle-Specific Pyruvate Kinase Isoforms, Pkm1 and Pkm2, Regulate Mammalian SWI/SNF Proteins and Histone 3 Phosphorylation During Myoblast Differentiation

Pyruvate kinase is a glycolytic enzyme that converts phosphoenolpyruvate and ADP into pyruvate and ATP. There are two genes that encode pyruvate kinase in vertebrates; Pkm and Pkl encode muscle- and liver/erythrocyte-specific forms, respectively. Each gene encodes two isoenzymes due to alternative splicing. Both muscle-specific enzymes, Pkm1 and Pkm2, function in glycolysis, but Pkm2 also has been implicated in gene regulation due to its ability to phosphorylate histone 3 threonine 11 (H3T11) in cancer cells. Here, we examined the roles of Pkm1 and Pkm2 during myoblast differentiation. RNA-seq analysis revealed that Pkm2 promotes the expression of Dpf2/Baf45d and Baf250a/Arid1A. Dpf2 and Baf250a are subunits that identify a specific sub-family of the mammalian SWI/SNF (mSWI/SNF) of chromatin remodeling enzymes that is required for activation of myogenic gene expression during differentiation. Pkm2 also mediated the incorporation of Dpf2 and Baf250a into the regulatory sequences controlling myogenic gene expression. Pkm1 did not affect expression but was required for nuclear localization of Dpf2. Additionally, Pkm2 was required not only for the incorporation of phosphorylated H3T11 in myogenic promoters, but also for the incorporation of phosphorylated H3T6 and H3T45 at myogenic promoters via regulation of AKT and protein kinase C isoforms that phosphorylate those amino acids. Our results identify multiple unique roles for Pkm2 and a novel function for Pkm1 in gene expression and chromatin regulation during myoblast differentiation.

Metadherin orchestrates PKA and PKM2 to activate β-catenin signaling in podocytes during proteinuric chronic kidney disease

Podocyte damage is the major cause of glomerular injury and proteinuria in multiple chronic kidney diseases. Metadherin (MTDH) is involved in podocyte apoptosis and promotes renal tubular injury in mouse models of diabetic nephropathy and renal fibrosis; however, its role in podocyte injury and proteinuria needs further exploration. Here, we show that MTDH was induced in the glomerular podocytes of patients with proteinuric chronic kidney disease and correlated with proteinuria. Podocyte-specific knockout of MTDH in mice reversed proteinuria, attenuated podocyte injury, and prevented glomerulosclerosis after advanced oxidation protein products challenge or adriamycin injury. Furthermore, specific knockout of MTDH in podocytes repressed β-catenin phosphorylation at the Ser675 site and inhibited its downstream target gene transcription. Mechanistically, on the one hand, MTDH increased cAMP and then activated protein kinase A (PKA) to induce β-catenin phosphorylation at the Ser675 site, facilitating the nuclear translocation of MTDH and β-catenin; on the other hand, MTDH induced the deaggregation of pyruvate kinase M2 (PKM2) tetramers and promoted PKM2 monomers to enter the nucleus. This cascade of events leads to the formation of the MTDH/PKM2/β-catenin/CBP/TCF4 transcription complex, thus triggering TCF4-dependent gene transcription. Inhibition of PKA activity by H-89 or blockade of PKM2 deaggregation by TEPP-46 abolished this cascade of events and disrupted transcription complex formation. These results suggest that MTDH induces podocyte injury and proteinuria by assembling the β-catenin-mediated transcription complex by regulating PKA and PKM2 function.

Cardioprotective potential of compound 3K, a selective PKM2 inhibitor in isoproterenol-induced acute myocardial infarction: A mechanistic study

Myocardial infarction (MI) or heart attack arises from acute or chronic prolonged ischemic conditions in the myocardium. Although several risk factors are associated with MI pathophysiology, one of the risk factors is an imbalance in the oxygen supply. The current available MI therapies are still inadequate due to the complexity of MI pathophysiology. Pyruvate kinase M2 (PKM2) has been implicated in numerous CVDs pathologies. However, the effect of specific pharmacological intervention targeting PKM2 has not been studied in MI. Therefore, in this study, we explored the effect of compound 3K, a PKM2-specific inhibitor, in isoproterenol-induced acute MI model. In this study, in order to induce MI in rats, isoproterenol (ISO) was administered at a dose of 100 mg/kg over two days at an interval of 24 h. Specific PKM2 inhibitor, compound 3K (2 and 4 mg/kg), was administered in MI rats to investigate its cardioprotective potential. After the last administration of compound 3K, ECG and hemodynamic parameters were recorded using a PV-loop system. Cardiac histology, western blotting, and plasmatic cardiac damage markers were evaluated to elucidate the underlying mechanisms. Treatment of compound 3K significantly reduced ISO-induced alterations in ECG, ventricular functions, cardiac damage, infarct size, and cardiac fibrosis. Compound 3K treatment produced significant increase in PKM1 expression and decrease in PKM2 expression. In addition, HIF-1α, caspase-3, c-Myc, and PTBP1 expression were also reduced after compound 3K treatment. This study demonstrates the cardioprotective potential of compound 3K in MI, and its mechanisms of cardioprotective action.

Epigenetic-based combination therapy and liposomal codelivery overcomes osimertinib-resistant NSCLC via repolarizing tumor-associated macrophages

Osimertinib (Osi) is widely used as a first-line treatment for non-small cell lung cancer (NSCLC) with EGFR mutations. However, the majority of patients treated with Osi eventually relapse within a year. The mechanisms of Osi resistance remain largely unexplored, and efficient strategies to reverse the resistance are urgently needed. Here, we developed a lactoferrin-modified liposomal codelivery system for the combination therapy of Osi and panobinostat (Pan), an epigenetic regulator of histone acetylation. We demonstrated that the codelivery liposomes could efficiently repolarize tumor-associated macrophages (TAM) from the M2 to M1 phenotype and reverse the epithelial-mesenchymal transition (EMT)-associated drug resistance in the tumor cells, as well as suppress glycolysis, lactic acid production, and angiogenesis. Our results suggested that the combination therapy of Osi and Pan mediated by liposomal codelivery is a promising strategy for overcoming Osi resistance in NSCLC.

PP4R1 promotes glycolysis and gallbladder cancer progression through facilitating ERK1/2 mediated PKM2 nuclear translocation

Gallbladder cancer (GBC) is a common solid tumor of the biliary tract with a high mortality rate and limited curative benefits from surgical resection. Here, we aimed to elucidate the pathogenesis of GBC from the perspective of molecular mechanisms and determined that protein phosphatase 4 regulator subunit 1 (PP4R1) is overexpressed in GBC tissues and contributes to poor prognosis. Through a series of in vitro and in vivo experiments, we demonstrated that PP4R1 overexpression improved tumorigenesis in GBC cells. Further mechanistic exploration revealed that PP4R1 directly interacts with pyruvate kinase-M2 (PKM2), a key regulator of glycolysis. PP4R1 promotes the extracellular signal-related kinase 1 and 2 (ERK1/2)-mediated PKM2 nuclear translocation, thereby participating in the regulation of tumor glycolysis. Interestingly, we determined that PP4R1 strengthens the interaction between ERK1/2 and PKM2. Furthermore, PP4R1 enhanced the suppressive effects of the ERK inhibitor SCH772984 on GBC. In conclusion, our data showed that PP4R1 is a promising biomarker associated with GBC and confirmed that PP4R1 regulates PKM2-mediated tumor glycolysis, which provides a metabolic growth advantage to GBC cells, thereby promoting GBC tumor growth and metastasis1.