Nuclear PKM2 regulates β-catenin transactivation upon EGFR activation

Intranuclear TCA and mitochondrial overload: The nascent sprout of tumors metabolism

Abnormal glucose metabolism in tumors is a well-known form of metabolic reprogramming in tumor cells, the most representative of which, the Warburg effect, has been widely studied and discussed since its discovery. However, contradictions in a large number of studies and suboptimal efficacy of drugs targeting glycolysis have prompted us to further deepen our understanding of glucose metabolism in tumors. Here, we review recent studies on mitochondrial overload, nuclear localization of metabolizing enzymes, and intranuclear TCA (nTCA) in the context of the anomalies produced by inhibition of the Warburg effect. We provide plausible explanations for many of the contradictory points in the existing studies, including the causes of the Warburg effect. Furthermore, we provide a detailed prospective discussion of these studies in the context of these new findings, providing new ideas for the use of nTCA and mitochondrial overload in tumor therapy.

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.

PRDX2 promotes gastric cancer progression by forming a feedback loop with PKM2/STAT3 axis

Peroxiredoxin 2 (PRDX2) is an antioxidant enzyme that has been reported to be overexpressed in various cancers. However, the role of PRDX2 in gastric cancer progression and its underlying mechanism remains unclear. Herein, we revealed the function of PRDX2 in gastric cancer progression and explored its molecule mechanism. We identified that PRDX2 was upregulated and associated with poor prognosis in gastric cancer. The knockdown of PRDX2 inhibited the proliferation, migration and invasion of gastric cancer cells in vitro and suppressed tumor growth in vivo. Mechanistically, PRDX2 interacted with PKM2 (pyruvate kinase isozyme type M2) and protected PKM2 from ubiquitination and degradation, which enhanced glycolysis in gastric cancer cells. The interaction between PRDX2 and PKM2 also enhanced the binding affinity between PKM2 and importin α5, which induced PKM2 nuclear translocation and activated STAT3 signaling pathway. In addition, STAT3 (signal transducer and activator of transcription 3) was identified to bind to PRDX2 gene promoter and upregulate PRDX2 expression, which forms a positive regulatory feedback loop in gastric cancer cells. The present study unravels the biological role of PRDX2 in cancer progression and illustrates the underlying molecular mechanism, which may provide a potential therapeutic target for gastric cancer.

PKM splice-switching ASOs induce upregulation of dual-specificity phosphatases and dephosphorylation of ERK1/2 in hepatocellular carcinoma

Pyruvate kinase M isoform 2 (PKM2) is preferentially expressed in nearly all cancers. It primarily functions as the last enzyme in glycolysis, but has other reported non-canonical functions, including recruiting transcription factors to oncogenes, and phosphorylating proteins. We previously described antisense oligonucleotides that disrupt alternative splicing of PKM pre-mRNA (PKM-ASOs), resulting in a PKM2-to-PKM1 isoform switch in hepatocellular carcinoma (HCC), which reduces HCC growth in vitro and in vivo. PKM1 has higher enzymatic activity than PKM2, which potentially drives metabolism away from macromolecule synthesis, and may explain decreased HCC growth upon PKM-ASO treatment. As PKM-ASOs also reduce PKM2 levels, how PKM splice-switching inhibits HCC cell proliferation was unclear. Here, we characterized the individual consequences of altering PKM1 or PKM2 protein levels in HCC, and observed that reducing PKM2 alone was sufficient to decrease HCC cell proliferation, whereas overexpressing PKM1 had no effect. Moreover, increasing PK activity via a small-molecule PKM2 activator had no effect on HCC cell proliferation, suggesting that PKM-ASOs affect PKM2's non-metabolic functions. Transcriptomic and RT-qPCR analyses of HCC cells treated with PKM-ASO or PKM2-siRNA revealed upregulation of dual-specificity phosphatase 2 (DUSP2) and other related DUSPs, which act directly on ERK1/2 in the MAPK signaling pathway. Luciferase reporter assays demonstrated that PKM-ASO treatment activated the DUSP2 promoter, which correlated with decreased ERK1/2 phosphorylation. Lenvatinib is a second-line HCC therapy that indirectly reduces ERK1/2 phosphorylation, and combined treatment with PKM-ASOs inhibited proliferation of HCC cells more than either treatment alone. In summary, our results reveal a mechanism by which PKM-ASOs affect PKM2 dependency in HCC.

EGFR and EGFRvIII coopt host defense pathways promoting progression in glioblastoma

BACKGROUND

Co-amplification of the epidermal growth factor receptor (EGFR) and EGFRvIII, a tumor-specific truncation mutant of EGFR, represent hallmark genetic lesions in glioblastoma.

METHODS

We used phospho-proteomics, RNA-sequencing, TCGA data, glioblastoma cell culture, and mouse models to study the signal transduction mediated by EGFR and EGFRvIII.

RESULTS

We report that EGFR and EGFRvIII stimulate the innate immune defense receptor Toll-like Receptor 2 (TLR2); and that knockout of TLR2 dramatically improved survival in orthotopic glioblastoma xenografts. EGFR and EGFRvIII activated TLR2 in a ligand-independent manner, promoting tumor growth and immune evasion. We show that EGFR and EGFRvIII cooperate to activate the Rho-associated protein kinase ROCK2, which modulated malignant progression both by activating TLR2 and WNT signaling, and through remodeling the tumor microenvironment.

CONCLUSIONS

Together, our findings show that EGFR and EGFRvIII cooperate to drive tumor progression through ROCK2 and downstream WNT-β-catenin/TLR2 signaling pathways.

ACSS2 acts as a lactyl-CoA synthetase and couples KAT2A to function as a lactyltransferase for histone lactylation and tumor immune evasion

Lactyl-coenzyme A (CoA)-dependent histone lysine lactylation impacts gene expression and plays fundamental roles in biological processes. However, mammalian lactyl-CoA synthetases and their regulation of histone lactylation have not yet been identified. Here, we demonstrate that epidermal growth factor receptor (EGFR) activation induces extracellular signal-regulated kinase (ERK)-mediated S267 phosphorylation of acetyl-CoA synthetase 2 (ACSS2) and its subsequent nuclear translocation and complex formation with lysine acetyltransferase 2A (KAT2A). Importantly, ACSS2 functions as a bona fide lactyl-CoA synthetase and converts lactate to lactyl-CoA, which binds to KAT2A as demonstrated by a co-crystal structure analysis. Consequently, KAT2A acts as a lactyltransferase to lactylate histone H3, leading to the expression of Wnt/β-catenin, NF-κB, and PD-L1 and brain tumor growth and immune evasion. A combination treatment with an ACSS2-KAT2A interaction-blocking peptide and an anti-PD-1 antibody induces an additive tumor-inhibitory effect. These findings uncover ACSS2 and KAT2A as hitherto unidentified lactyl-CoA synthetase and lactyltransferase, respectively, and the significance of the ACSS2-KAT2A coupling in gene expression and tumor development.

ADSL promotes autophagy and tumor growth through fumarate-mediated Beclin1 dimethylation

As an enzyme with a critical role in de novo purine synthesis, adenylosuccinate lyase (ADSL) expression is upregulated in various malignancies. However, whether ADSL possesses noncanonical functions that contribute to cancer progression remains poorly understood. Here, we demonstrate that protein kinase R-like endoplasmic reticulum kinase (PERK) activated by lipid deprivation or ER stress phosphorylates ADSL at S140, leading to an enhanced association between ADSL and Beclin1. Beclin1-associated ADSL produces fumarate, which in turn inhibits lysine demethylase 8-mediated Beclin1 demethylation, resulting in enhanced Beclin1 K117me2, subsequent disruption of the binding of BCL-2 to Beclin1 and elevated autophagy. Blocking the ADSL-Beclin1 axis by knock-in mutation or a cell-penetrating peptide inhibits autophagy induced by lipid deprivation and ER stress and blunts liver tumor growth in mice. Additionally, ADSL pS140-upregulated Beclin1 K117me2 levels are positively correlated with autophagy levels in human hepatocellular carcinoma specimens and poor patient prognosis. These findings uncover the function of ADSL in autophagy regulation and liver tumor development.

HACD2 Promotes Pancreatic Cancer Progression by Enhancing PKM2 Dissociation From PRKN in a Dehydratase-Independent Manner

3-Hydroxyacyl-CoA dehydratase 2 (HACD2), an obesity-related gene involved in the elongation of long-chain fatty acids, is highly expressed in pancreatic cancer (PC) and is associated with patient prognosis. Interestingly, the study reveals that HACD2 mediated the proliferation of PC cells in a dehydratase-independent manner, affecting the downstream glycolytic pathway. Mechanistically, HACD2 promotes PC cells proliferation by binding to E3 ubiquitin-protein ligase parkin (PRKN) and enhancing pyruvate kinase PKM (PKM2) dissociation from PRKN, resulting in reduced ubiquitination of PKM2 and increased dimerization of PKM2, which subsequently promote c-Myc expression and tumor growth. Moreover, HACD2 overexpression-induced PC growth is mitigated by knockdown of PKM2 or overexpression of PRKN. Furthermore, the weight loss drug orlistat, which potentially binds to HACD2, disrupted the interaction between HACD2 and PRKN and further increased the ubiquitination of PKM2. Therefore, this study elucidates the mechanism by which the obesity-related gene HACD2 regulates PC cells proliferation through a noncanonical signaling pathway, which may provide a potential new target and strategy for the individualized clinical treatment of PC.

PKM2-mediated collagen XVII expression is critical for wound repair

Chronic wounds have emerged as a tough clinical challenge. An improved understanding of wound-healing mechanisms is paramount. Collagen XVII (COL17), a pivotal constituent of hemidesmosomes, holds considerable promise for regulating epidermal cell adhesion to the basement membrane as well as for epidermal cell motility and self-renewal of epidermal stem cells. However, the precise role of COL17 in wound repair remains elusive, and the upstream regulatory mechanisms involved have not been fully elucidated. In this study, we delineated the temporal and spatial expression patterns of COL17 at the epidermal wound edge. Subsequently, we investigated the indispensable role of COL17 in keratinocyte activation and reepithelialization during wound healing, demonstrating the restoration of the normal repair process by COL17 overexpression in diabetic wounds. Notably, we identified a key transcriptional signaling pathway for COL17, wherein pyruvate kinase isozyme M2 (PKM2) promotes phosphorylation of STAT3, leading to its activation and subsequent induction of COL17 expression upon injury. Ultimately, by manipulating this pathway using the PKM2 nuclear translocator SAICAR, we revealed a promising therapeutic strategy for enhancing the healing of chronic wounds.

Increased Plasma Pyruvate Kinase M2 (PK-M2) in Heart Failure: A Novel Biomarker Related to Cardiac Function and its Clinical Implications

BACKGROUND

The purpose of this study was to investigate whether circulating pyruvate kinase M2 (PK-M2) levels are elevated in the peripheral blood and to assess their association with diagnosis and prognosis in patients with heart failure (HF).

METHODS AND RESULTS

We conducted a prospective investigation involving 222 patients with HF and 103 control subjects, measuring PK-M2 concentrations using ELISA. The primary outcome, assessed over a median follow-up of 2 years (interquartile range: 776 to 926 days), was the time to the first occurrence of either rehospitalization for worsening HF or cardiovascular death. Patients with HF had higher PK-M2 levels than controls (17.4±4.1 versus 7.8±2.3 U/mL, P <0.001), and these levels correlated with HF severity (New York Heart Association cardiac function class). Patients with reduced left ventricular ejection fraction had higher PK-M2 concentrations than those with preserved ejection fraction (18.3±4.5 versus 16.7±3.6 U/mL, P <0.01). In a subset of patients with HF (n=52), PK-M2 levels significantly decreased following standardized HF treatment (mean difference, -4.3±0.5 U/mL, P <0.001). A high PK-M2 level had a 1.913-fold higher risk of the primary outcome (P=0.033) after adjusting for multiple cardiovascular risk factors, but not with cardiovascular death. Additionally, PK-M2 added incremental prognostic value beyond clinical predictors and N-terminal pro-brain natriuretic peptide (P <0.05).

CONCLUSIONS

Elevated PK-M2 levels are associated with primary outcomes and rehospitalization for worsening heart failure in patients with HF. These findings suggest that PK-M2 is a potential biomarker for HF diagnosis and prognosis, warranting consideration for serial patient assessment.

LDHAα, a lactate dehydrogenase A isoform, promotes glycolysis and tumor progression

Lactate dehydrogenase A (LDHA) is upregulated in multiple cancer types and contributes to the Warburg effect. Several studies have found that many tumor-related genes have subtypes and play important roles in promoting cancer development. Here, we identified a novel LDHA transcript, which produced a new protein 3 kDa larger than LDHA, which we named LDHAα. We found that multiple cancer cell lines express LDHAα, and ectopic expression of LDHAα led to a higher proliferation and migration rate in vitro. Ectopic expression of LDHAα could also promote tumor cell growth in vivo. Conversely, deletion of LDHAα by CRISPR-sgRNA significantly inhibited the growth of tumor cells. LDHAα was found to be mainly located in the cytoplasm, and overexpression or deletion of LDHAα could significantly affect the glucose uptake and lactate production of tumor cells. Further investigation showed that c-MYC and FOXM1 could markedly modulate the expression of both LDHA and LDHAα, especially c-MYC. We found that a small molecular compound targeting LDHA could also inhibit the enzyme activity of LDHAα. LDHAα, LDHA and c-MYC expression was significantly higher in human acute lymphocytic leukemia and colorectal cancer tissue specimens compared to normal controls. In conclusion, our study identified LDHAα as a subtype of LDHA and highlighted its critical role in tumor metabolism, providing a potential new therapeutic target for tumor diagnosis and treatment.

ERK-USP9X-coupled regulation of thymidine kinase 1 promotes both its enzyme activity-dependent and its enzyme activity-independent functions for tumor growth

Thymidine kinase 1 (TK1), a crucial enzyme in DNA synthesis, is highly expressed in various cancers. However, the mechanisms underlying its elevated expression and the implications for tumor metabolism remain unclear. Here we demonstrate that activation of growth factor receptors enhances TK1 expression. Treatment with epidermal growth factor or insulin-like growth factor 1 induces the binding of ERK1/2 to TK1 and subsequent TK1 S13/231 phosphorylation by ERK1/2. This modification recruits ubiquitin carboxyl-terminal hydrolase 9X to deubiquitylate TK1, preventing its proteasomal degradation. Stabilized TK1 not only enhances its enzyme activity-dependent deoxythymidine monophosphate production for DNA synthesis but also promotes glycolysis independently of its enzymatic activity by upregulating phosphofructokinase/fructose bisphosphatase type 3 expression. This dual role of TK1 drives the proliferation of human hepatocellular carcinoma cells and liver tumor growth in mice. Our findings reveal a crucial mechanism by which growth factors promote tumor development through TK1-mediated DNA synthesis and glycolysis and highlight TK1 as a potential molecular target for cancer treatment.

The protein circPETH-147aa regulates metabolic reprogramming in hepatocellular carcinoma cells to remodel immunosuppressive microenvironment

Metabolic reprogramming fuels cancer cell metastasis and remodels the immunosuppressive tumor microenvironment (TME). We report here that circPETH, a circular RNA (circRNA) transported via extracellular vesicles (EVs) from tumor-associated macrophages (TAMs) to hepatocellular carcinoma (HCC) cells, facilitates glycolysis and metastasis in recipient HCC cells. Mechanistically, circPETH-147aa, encoded by circPETH in an m6A-driven manner, promotes PKM2-catalyzed ALDOA-S36 phosphorylation via the MEG pocket. Furthermore, circPETH-147aa impairs anti-HCC immunity by increasing HuR-dependent SLC43A2 mRNA stability and driving methionine and leucine deficiency in cytotoxic CD8+ T cells. Importantly, through virtual and experimental screening, we find that a small molecule, Norathyriol, is an effective inhibitor that targets the MEG pocket on the circPETH-147aa surface. Norathyriol reverses circPETH-147aa-facilitated acquisition of metabolic and metastatic phenotypes by HCC cells, increases anti-PD1 efficacy, and enhances cytotoxic CD8+ T-cell function. Here we show that Norathyriol is a promising anti-HCC agent that contributes to attenuating the resistance of advanced HCC to immune checkpoint blocker (ICB) therapies.

Nucleus-translocated GCLM promotes chemoresistance in colorectal cancer through a moonlighting function

Metabolic enzymes perform moonlighting functions during tumor progression, including the modulation of chemoresistance. However, the underlying mechanisms of these functions remain elusive. Here, utilizing a metabolic clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 knockout library screen, we observe that the loss of glutamate-cysteine ligase modifier subunit (GCLM), a rate-limiting enzyme in glutathione biosynthesis, noticeably increases the sensitivity of colorectal cancer (CRC) cells to platinum-based chemotherapy. Mechanistically, we unveil a noncanonical mechanism through which nuclear GCLM competitively interacts with NF-kappa-B (NF-κB)-repressing factor (NKRF), to promote NF-κB activity and facilitate chemoresistance. In response to platinum drug treatment, GCLM is phosphorylated by P38 MAPK at T17, resulting in its recognition by importin a5 and subsequent nuclear translocation. Furthermore, elevated expression of nuclear GCLM and phospho-GCLM correlate with an unfavorable prognosis and poor benefit from standard chemotherapy. Overall, our work highlights the essential nonmetabolic role and posttranslational regulatory mechanism of GCLM in enhancing NF-κB activity and subsequent chemoresistance.

Bioinformatics analysis of PSAT1 loss identifies downstream pathways regulated in EGFR mutant NSCLC and a selective gene signature for predicting the risk of relapse

The majority of malignant tumors exhibit an altered metabolic phenotype that ultimately provides the required energy and molecular precursors necessary for unregulated cell division. Within this, phosphoserine aminotransferase 1 (PSAT1) is involved in de novo serine biosynthesis and its activity promotes various biochemical processes, including one-carbon metabolism. It also directly generates α-ketoglutarate (α-KG), a Kreb cycle intermediate and epigenetic-regulating metabolite. Prior studies examining PSAT1 depletion have identified individual affected downstream pathways, such as GSK3β and E2F, in several cancer types, including non-small-cell lung cancer (NSCLC). However, global gene expression examination in response to PSAT1 loss, particularly in EGFR mutant NSCLC, has not been unexplored. Transcriptional profiling of EGFR mutant NSCLC cells with or without stable knock-down of PSAT1 identified differentially expressed genes (DEGs) enriched in several metabolic pathways required for cell division, including amino acid and nucleotide biosynthesis. Supplementation studies involving non-essential amino acids, nucleosides and α-KG partially restored defects in anchorage-independent growth due to the knockdown of PSAT1. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology enrichment analysis identified potential impacts on actin cytoskeleton arrangement and β-catenin activity, which were rescued by PSAT1 re-expression. Finally, a comparative analysis of PSAT1 DEGs against transcripts enriched in patient EGFR mutant lung tumors identified a gene signature that is associated with overall and relapse-free survival (RFS) and was able to distinguish low or high-risk populations for RFS in early-stage EGFR mutant NSCLC. Overall, investigating genes altered by PSAT1 loss confirmed known PSAT1-regulated cellular pathways, identified a previously unknown role in the mediation of cytoskeleton arrangement in EGFR mutant NSCLC cells and allowed for the characterization of a gene signature with putative predictive potential for RFS in early-stage disease.

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.

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 NF-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.

Emodin disrupts the KITENIN oncogenic complex by binding ErbB4 and suppresses colorectal cancer progression in dual blockade with KSRP-binding compound

BACKGROUND

The KITENIN/ErbB4 complex has been reported to participate in metastasis, which is the principal reason of death in most colorectal cancer patients.

PURPOSE

New therapeutics need to be developed to suppress the malignant effects of the KITENIN/ErbB4 complex, which is related to drug resistance. The present study aimed to evaluate changes in cancer cell invasion capacity, transcriptional regulators, and cellular bioenergetics after targeting the KITENIN/ErbB4 complex with emodin. Moreover, we aimed to reveal the mechanistic effects of emodin and observe the dual blockade effects of ErbB4-targeted therapy with KH-type splicing regulatory protein (KSRP) and search for new alternative blockade pathways.

METHODS

Using in vitro, in vivo, molecular-docking, and metabolomics studies, we evaluated the anticancer effect of emodin alone or in combination with DKCC14S.

RESULTS

Emodin treatment decreased KITENIN and ErbB4 protein levels. The dysfunctional KITENIN/ErbB4 complex suppressed KITENIN-mediated cell invasion and downregulated AP-1 activity, aerobic glycolysis, and the levels of transcriptional regulators associated with cell metabolism. We conclude that emodin targets the KITENIN/ErbB4 complex and offering a novel mechanism by which it disrupts KITENIN-mediated signaling. Furthermore, we were demonstrated that the dual blocking effect of emodin and DKC-C14S on the KITENIN complex showed synergistic effects in suppressing colorectal cancer progression under in cell-based and animal assay.

CONCLUSION

The results suggest that co-treatment with ErbB4 and KSRP-binding compounds could constitute a potential strategy for controlling colorectal cancer progression by disrupting the KITENIN complex.

Cell metabolism-based therapy for liver fibrosis, repair, and hepatocellular carcinoma

Progression of chronic liver injury to fibrosis, abnormal liver regeneration, and HCC is driven by a dysregulated dialog between epithelial cells and their microenvironment, in particular immune, fibroblasts, and endothelial cells. There is currently no antifibrogenic therapy, and drug treatment of HCC is limited to tyrosine kinase inhibitors and immunotherapy targeting the tumor microenvironment. Metabolic reprogramming of epithelial and nonparenchymal cells is critical at each stage of disease progression, suggesting that targeting specific metabolic pathways could constitute an interesting therapeutic approach. In this review, we discuss how modulating intrinsic metabolism of key effector liver cells might disrupt the pathogenic sequence from chronic liver injury to fibrosis/cirrhosis, regeneration, and HCC.

Extracellular PKM2 Preserves Cardiomyocytes and Reduces Cardiac Fibrosis During Myocardial Infarction

Substantial loss of cardiomyocytes during heart attacks and onset of other cardiovascular diseases is a major cause of mortality. Preservation of cardiomyocytes during cardiac injury would be the most effective strategy to manage these diseases in clinic. However, there is no effective treatment strategy that is able to prevent cardiomyocyte loss. We demonstrate here that the systemic administration of a recombinant PKM2 mutant (G415R) preserves cardiomyocytes and reduces cardiac fibrosis during myocardial infarction. G415R preserves cardiomyocytes by protecting the cardiomyocytes from dying and by promoting cardiomyocyte proliferation. Preservation of cardiomyocytes by extracellular PKM2 (EcPKM2) reduces cardiac fibrosis because of the decreased activation of cardiac fibroblasts. Our experiments show that EcPKM2 (G415R) exerts its action by interacting with integrin avb3 on cardiomyocytes. EcPKM2(G415R) activates the integrin-FAK-PI3K signaling axis, which subsequently suppresses PTEN expression and consequently regulates cardiomyocyte apoptosis resistance and proliferation under hypoxia and oxidative stress conditions. Our studies uncover an important cardiomyocyte protection mechanism. More importantly, the activity/action of EcPKM2 (G415R) in preserving cardiomyocyte suggesting a possible therapeutic strategy and target for the treatment of heart attacks and other cardiovascular diseases.

The mechanism of sevoflurane affecting ovarian cancer cell proliferation and migration by regulating RNA methylase TRDMT1 to activate the β-catenin pathway

OBJECTIVE

Sevoflurane (Sevo), a commonly used inhalant anesthetic clinically, is associated with a worsened cancer prognosis, and we investigated its effect on RNA methylase tRNA aspartic acid methyltransferase 1 (TRDMT1) expression and ovarian cancer (OC) cell malignant phenotypes.

METHODS

Human OC cells (OVCAR3/SKOV3) were pretreated with 3.6% Sevo and cultured under normal conditions for 48 h, with their viability assessed. After 2-h Sevo treatment or interference plasmid transfections to down-regulate TRDMT1/adenomatous polyposis coli (APC), changes in TRDMT1, APC and β-catenin expression, cell proliferative activity, cycle, apoptosis, migration, invasion, and 5-methylcytosine (m5C) methylation potential modification sites were evaluated. Additionally, APC mRNA m5C methylation level and stability, the binding of APC mRNA with TRDMT1, the binding intensity of APC and β-catenin, and β-catenin nuclear translocation were detected Lastly, Cyclin D1, cellular-myelocytomatosis viral oncogene (C-myc) and β-catenin protein levels, and ki67-positive rate were assessed.

RESULTS

Sevo treatment boosted cell cycle, proliferation, migration and invasion, suppressed apoptosis and APC expression, and up-regulated C-myc, β-catenin, TRDMT1 and Cyclin D1 levels. Silencing TRDMT1 or β-catenin partially averted Sevo-mediated promotion effects on cell malignant biological behaviors. Lowly-expressed APC annulled the effect of silencing TRDMT1 and promoted cell malignant behaviors. Sevo enhanced APC mRNA m5C modification and degradation and activated the APC/β-catenin pathway by increasing TRDMT1, thus encouraging OC growth in vivo.

CONCLUSIONS

Sevo stimulated APC m5C modification and curbed its expression by up-regulating TRDMT1, which in turn activated the β-catenin pathway to stimulate OC cell cycle, invasion, proliferation, and migration and to suppress apoptosis.

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.

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.

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.

The wnt/pyruvate kinase, muscle axis plays an essential role in the differentiation of mouse neuroblastoma cells

Neuronal differentiation and neurite growth are essential processes in nervous system development and are regulated by several factors. Although all-trans retinoic acid (ATRA) has been shown to mediate the differentiation of mouse neuroblastoma cells via the activation of several pathways, including Wnt/β-catenin signaling, the mechanism remains unclear. The pyruvate kinase, muscle (PKM) plays an important role in the glycolysis of neuroblastoma cells and regulates the Wnt signaling pathway in various cancer cells. In this study, we hypothesized that the Wnt/PKM axis regulates the differentiation of neuroblastoma cells (Neuro-2a and N1E-115). To test this hypothesis, we used inhibitors and activators of the Wnt/β-catenin and glycolytic pathways in ATRA-induced differentiated Neuro-2a and N1E-115 cells and established cell lines with silenced or a mutant replacement of Pkm. Western blot and qPCR showed that ATRA treatment activated the Wnt signaling pathway and inhibited PKM-mediated glycolysis. The oxygen consumption rate (indicating oxidative phosphorylation) significantly increased, whereas the extracellular acidification rate (indicating glycolysis) significantly decreased during differentiation; these effects were reversed upon PKM inhibition. The Wnt inhibitor ICG-001 and PKM activator ML-265 inhibited ATRA-induced Neuro-2a and N1E-115 differentiation, whereas RNA interference-mediated Pkm silencing promoted Neuro-2a and N1E-115 differentiation, which was reversed by PKM overexpression. Treatment with the Wnt activator kenpaullone promoted Neuro-2a and N1E-115 differentiation, which was reversed by ML-265 administration. These results indicate that Wnt/β-catenin signaling promotes Neuro-2a and N1E-115 differentiation by inhibiting PKM-mediated glycolysis during ATRA-induced differentiation. These findings may provide a new theoretical basis for the role of glycolysis in nerve differentiation.

Interplay of CDKs and cyclins with glycolytic regulatory enzymes PFK and PK

In plants, as in all eukaryotes, the cell cycle is regulated by the heterodimer formed by cyclins (Cycs) and cyclin-dependent kinases (CDKs), that phosphorylate serine/threonine residues in target proteins. The extensive involvement of these heterodimers in nuclear cell cycle-related processes has been demonstrated. However, recent findings have linked Cyc-CDK complexes to the regulation of cytosolic processes, including various metabolic pathways, suggesting close coordination between the cell cycle and catabolic/anabolic processes to maintain cellular energy homeostasis. This study extends the analysis of Cyc-CDK complex regulation in maize to two key regulators of glycolysis: phosphofructose kinase (PFK) and pyruvate kinase (PK). Both are cytosolic enzymes, highly regulated positively and negatively by different metabolites, showing a similar activation pattern in their homotetrameric form and low activity when as dimers/monomers. Each enzyme exhibits two putative minimal phosphorylation motives for Cyc-CDKs, conserved in some plant species and in four (PFK) and three (PK) isoforms in maize. This work demonstrates that both enzymes are active with fluctuating levels of activity along maize germination; also, that they associate with different maize Cycs and CDKs as demonstrated by pull-down assays, as well as their in vitro phosphorylation by recombinant CycD;2-CDKA or CycD2;2-CDKB complexes. Additionally, the inhibition of PFK and PK activity following phosphorylation by active Cycs-CDKB complexes obtained by immunoprecipitation from imbibed embryonic axis protein extracts suggests a narrow and negative regulation of glycolysis as the cell cycle progresses. A decreased carbon flow through this pathway is proposed to divert carbon from sugars towards the oxidative pentose phosphate pathway, thereby promoting de novo nucleic acid synthesis precursors to stimulate cell cycle progression.

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.

EGF/EGFR-YAP1/TEAD2 signaling upregulates STIM1 in vemurafenib resistant melanoma cells

Stromal interaction molecule 1 (STIM1) is the endoplasmic reticulum Ca2+ sensor for store-operated calcium entry and is closely associated with carcinogenesis and tumor progression. Previously, we found that STIM1 is upregulated in melanoma cells resistant to the serine/threonine-protein kinase B-raf inhibitor vemurafenib, although the mechanism underlying this upregulation is unknown. Here, we show that vemurafenib resistance upregulates STIM1 through an epidermal growth factor (EGF)/epidermal growth factor receptor (EGFR)-Yes-associated protein 1 (YAP1)/TEA domain transcription factor 2 (TEAD2) signaling axis. Vemurafenib resistance can lead to an increase in EGF and EGFR levels, causing activation of the EGFR signaling pathway, which promotes YAP1 nuclear localization to increase the expression of STIM1. Our findings not only reveal the mechanism by which vemurafenib resistance promotes STIM1 upregulation, but also provide a rationale for combined targeting of the EGF/EGFR-YAP1/TEAD2-STIM1 axis to improve the therapeutic efficacy of BRAF inhibitor in melanoma patients.

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.

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.

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.

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.

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.