PKM2, cancer metabolism, and the road ahead

Dihydroartemisinin enhances the anti-tumour effect of photodynamic therapy by targeting PKM2-mediated glycolysis in oesophageal cancer cell

Photodynamic therapy (PDT) has been demonstrated to provide immediate relief of oesophageal cancer patients' re-obstruction and extend their lifespan. However, tumour regrowth may occur after PDT due to enhanced aerobic glycolysis. Previous research has confirmed the inhibitory effect of Dihydroartemisinin (DHA) on aerobic glycolysis. Therefore, the current study intends to investigate the function and molecular mechanism of DHA targeting tumour cell aerobic glycolysis in synergia PDT. The combined treatment significantly suppressed glycolysis in vitro and in vivo compared to either monotherapy. Exploration of the mechanism through corresponding experiments revealed that pyruvate kinase M2 (PKM2) was downregulated in treated cells, whereas overexpression of PKM2 nullified the inhibitory effects of DHA and PDT. This study proposes a novel therapeutic strategy for oesophageal cancer through DHA-synergized PDT treatment, targeting inhibit PKM2 to reduce tumour cell proliferation and metastasis.

PKM2 promotes myoblast growth and inosine monophosphate-specific deposition in Jingyuan chicken

Inosine monophosphate (IMP) is widely regarded as an important indicator for evaluating the flavour of poultry meat. However, little is known about the molecular mechanisms affecting the specific deposition of IMP. In this study, we functionally verified PKM2 (Pyruvate kinase M2), a candidate gene related to IMP synthesis, in order to reveal the important role of PKM2 in meat flavour and muscle development of Jingyuan chickens. The results showed that the IMP content in breast muscle of Jingyuan chickens was negatively correlated with PKM2 mRNA expression (r = -0.1710), while the IMP content in leg muscle was significantly positively correlated with PKM2 mRNA expression (r = 0.7350) (P < 0.05). During myogenesis, PKM2 promoted the proliferation rate of myoblasts and the expression of proliferation marker genes, inhibited the apoptosis rate and the expression of apoptosis marker genes, and decreased the expression of differentiation marker genes. Up-regulation of PKM2 enhanced the expression of key genes in the purine metabolic pathway and the de novo synthesis pathway of IMP, and suppressed the expression of key genes in the salvage pathway. ELISA assays showed that PKM2 decreased IMP and hypoxanthine (HX) contents, while adenosine triphosphate (ATP) and uric acid (UA) contents were clearly elevated. In summary, these studies revealed that PKM2 regulates myogenesis and specific deposition of IMP, which can be used to improve the quality of Jingyuan chicken meat.

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.

FV-429 induces apoptosis by regulating nuclear translocation of PKM2 in pancreatic cancer cells

Of all malignancies, pancreatic ductal adenocarcinoma (PDAC), constituting 90% of pancreatic cancers, has the worst prognosis. Glycolysis is overactive in PDAC patients and is associated with poor prognosis. Drugs that inhibit glycolysis as well as induce cell death need to be identified. However, glycolysis inhibitors often fail to induce cell death. We here found that FV-429, a derivative of the natural flavonoid wogonin, can induce mitochondrial apoptosis and inhibit glycolysis in PDAC in vivo and in vitro. In vitro, FV-429 inhibited intracellular ATP content, glucose uptake, and lactate generation, consequently leading to mitochondrial dysfunction and apoptosis in PDAC cells. Furthermore, it decreased the expression of PKM2 (a specific form of pyruvate kinase) through the ERK signaling pathway and enhanced PKM2 nuclear translocation. TEPP-46, the activator of PKM2, reversed FV-429-induced glycolysis inhibition and mitochondrial apoptosis in the PDAC cells. In addition, FV-429 exhibited significant tumor suppressor activity and high safety in BxPC-3 cell xenotransplantation models. These results thus demonstrated that FV-429 decreases PKM2 expression through the ERK signaling pathway and enhances PKM2 nuclear translocation, thereby resulting in glycolysis inhibition and mitochondrial apoptosis in PDAC in vitro and in vivo, which makes FV-429 a promising candidate for pancreatic cancer treatment.

Integrative proteomic and transcriptomic analysis in the female goat ovary to explore the onset of puberty

Puberty is considered a prerequisite for affecting reproductive performance and productivity. Little was known about molecular changes in pubertal goat ovaries. Therefore, we measured and performed a correlation analysis of the mRNA and proteins changes in the pre-pubertal and pubertal goat ovaries. The results showed that only six differentially expressed genes and differentially abundant proteins out of 18,139 genes and 7550 proteins quantified had significant correlations. CNTN2 and THBS1, discovered in the mRNA-mRNA interaction network, probably participated in pubertal and reproductive regulation by influencing GnRH receptor signals, follicular development, and ovulation. The predicted core transcription factors may either promote or inhibit the expression of reproductive genes and act synergistically to maintain normal reproductive function in animals. The interaction between PKM and TIMP3 with other proteins may impact animal puberty through energy metabolism and ovarian hormone secretion. Pathway enrichment analyses revealed that the co-associated key pathways between ovarian genes and proteins at puberty included calcium signalling pathway and olfactory transduction. These pathways were associated with gonadotropin-releasing hormone synthesis and secretion, signal transmission, and cell proliferation. In summary, these results enriched the potential molecules and signalling pathways that affect puberty and provided new insights for regulating and promoting the onset of puberty. SIGNIFICANCE: This study conducted the first transcriptomic and proteomic correlation analysis of pre-pubertal and pubertal goat ovaries and identified six significantly correlated molecules at both the gene and protein levels. Meanwhile, we were drawn to several molecules and signalling pathways that may play a regulatory role in the onset of puberty and reproduction by influencing reproductive-related gene expression, GnRH receptor signals, energy metabolism, ovarian hormone secretion, follicular development, and ovulation. This information contributed to identify potential biomarkers in pubertal goat ovaries, which was vital for predicting the onset of puberty and improving livestock performance.

AKR1B10 accelerates glycolysis through binding HK2 to promote the malignant progression of oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) remains a rampant oral cavity neoplasm with high degree of aggressiveness. Aldo-keto reductase 1B10 (AKR1B10) that is an oxidoreductase dependent on nicotinamide adenine dinucleotide phosphate (NADPH) has been introduced to possess prognostic potential in OSCC. The present work was focused on specifying the involvement of AKR1B10 in the process of OSCC and its latent functional mechanism.

METHODS

AKR1B10 expression in OSCC tissues and cells were detected by RT-qPCR and Western blot analysis. CCK-8 method, EdU staining, wound healing and transwell assays respectively assayed cell viability, proliferation, migration and invasion. Immunofluorescence staining and Western blot evaluated epithelial mesenchymal transition (EMT). Adenosine triphosphate (ATP) contents, glucose consumption and extracellular acidification rate (ECAR) were measured by relevant commercially available kits and Seahorse XF96 Glycolysis Analyzer, severally. The expressions of proteins associated with metastasis and glycolysis were examined with Western blot. Co-IP assay confirmed the binding between AKR1B10 and hexokinase 2 (HK2).

RESULTS

It was observed that AKR1B10 expression was increased in OSCC tissues and cells. After AKR1B10 was knocked down, the proliferation, migration, invasion and EMT of OSCC cells were all hampered. Additionally, AKR1B10 silencing suppressed glycolysis and bound to HK2 in OSCC cells. Up-regulation of HK2 partially abolished the hampered glycolysis, proliferation, migration, invasion and EMT of AKR1B10-silenced OSCC cells.

CONCLUSION

To sum up, AKR1B10 could bind to HK2 to accelerate glycolysis, thereby facilitating the proliferation, migration, invasion and EMT of OSCC cells.

Protein neddylation and its role in health and diseases

NEDD8 (Neural precursor cell expressed developmentally downregulated protein 8) is an ubiquitin-like protein that is covalently attached to a lysine residue of a protein substrate through a process known as neddylation, catalyzed by the enzyme cascade, namely NEDD8 activating enzyme (E1), NEDD8 conjugating enzyme (E2), and NEDD8 ligase (E3). The substrates of neddylation are categorized into cullins and non-cullin proteins. Neddylation of cullins activates CRLs (cullin RING ligases), the largest family of E3 ligases, whereas neddylation of non-cullin substrates alters their stability and activity, as well as subcellular localization. Significantly, the neddylation pathway and/or many neddylation substrates are abnormally activated or over-expressed in various human diseases, such as metabolic disorders, liver dysfunction, neurodegenerative disorders, and cancers, among others. Thus, targeting neddylation becomes an attractive strategy for the treatment of these diseases. In this review, we first provide a general introduction on the neddylation cascade, its biochemical process and regulation, and the crystal structures of neddylation enzymes in complex with cullin substrates; then discuss how neddylation governs various key biological processes via the modification of cullins and non-cullin substrates. We further review the literature data on dysregulated neddylation in several human diseases, particularly cancer, followed by an outline of current efforts in the discovery of small molecule inhibitors of neddylation as a promising therapeutic approach. Finally, few perspectives were proposed for extensive future investigations.

Icaritin activates p53 and inhibits aerobic glycolysis in liver cancer cells

Metabolic reprogramming enables cancer cells to generate energy mainly through aerobic glycolysis, which is achieved by increasing the expression levels of glycolysis-related enzymes. Therefore, the development of drugs targeting aerobic glycolysis could be an effective strategy for cancer treatment. Icaritin (ICT) is an active ingredient from the Chinese herbal plant Epimedium with several biological activities, but its anti-cancer mechanism remains inconclusive. Using normal hepatocytes and hepatoma cells, our results showed that ICT suppressed cell proliferation and clonal formation and decreased glucose consumption and lactate production in liver cancer cells. In consistent, the mRNA and protein levels of several aerobic glycolysis-related genes were decreased upon ICT treatment. Furthermore, our results demonstrated that the expression levels of the aerobic glycolysis-related proteins were correlated with the p53 status in hepatoma cells. Using PFT-α or siRNA-p53, our results confirmed that ICT regulated aerobic glycolysis in a p53-dependent manner. In addition, ICT was found to stabilize p53 at the post-translational level which might be mediated by inhibiting MDM2 expression and affecting its interaction with p53. Finally, our results demonstrated that ICT increased the levels of ROS that activated p53 via the p38 MAPK pathway. In conclusion, ICT increased intracellular ROS levels in liver cancer cells, which promoted the stabilization and activation of p53, inhibiting the expression of aerobic glycolysis-related genes and glycolysis, and ultimately leading to the suppression of liver cancer development.

PKM2 diverts glycolytic flux in dependence on mitochondrial one-carbon cycle

Modeling tumor metabolism in vitro remains challenging. Here, we used galactose as an in vitro tool compound to mimic glycolytic limitation. In contrast to the established idea that high glycolytic flux reduces pyruvate kinase isozyme M2 (PKM2) activity to support anabolic processes, we have discovered that glycolytic limitation also affects PKM2 activity. Surprisingly, despite limited carbon availability and energetic stress, cells induce a near-complete block of PKM2 to divert carbons toward serine metabolism. Simultaneously, TCA cycle flux is sustained, and oxygen consumption is increased, supported by glutamine. Glutamine not only supports TCA cycle flux but also serine synthesis via distinct mechanisms that are directed through PKM2 inhibition. Finally, deleting mitochondrial one-carbon (1C) cycle reversed the PKM2 block, suggesting a potential formate-dependent crosstalk that coordinates mitochondrial 1C flux and cytosolic glycolysis to support cell survival and proliferation during nutrient-scarce conditions.

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.

CD8+ T cell metabolic flexibility elicited by CD28-ARS2 axis-driven alternative splicing of PKM supports antitumor immunity

Metabolic flexibility has emerged as a critical determinant of CD8+ T-cell antitumor activity, yet the mechanisms driving the metabolic flexibility of T cells have not been determined. In this study, we investigated the influence of the nuclear cap-binding complex (CBC) adaptor protein ARS2 on mature T cells. In doing so, we discovered a novel signaling axis that endows activated CD8+ T cells with flexibility of glucose catabolism. ARS2 upregulation driven by CD28 signaling reinforced splicing factor recruitment to pre-mRNAs and affected approximately one-third of T-cell activation-induced alternative splicing events. Among these effects, the CD28-ARS2 axis suppressed the expression of the M1 isoform of pyruvate kinase in favor of PKM2, a key determinant of CD8+ T-cell glucose utilization, interferon gamma production, and antitumor effector function. Importantly, PKM alternative splicing occurred independently of CD28-driven PI3K pathway activation, revealing a novel means by which costimulation reprograms glucose metabolism in CD8+ T cells.

p53-dependent HIF-1α /autophagy mediated glycolysis to support Cr(VI)-induced cell growth and cell migration

Cr(VI) is known to be seriously toxic and carcinogenic. Hypoxia-inducible factor-1α (HIF-1α) is a crucial regulator to promote tumor development. In this study, we found that Cr(VI) significantly increased the expression of HIF-1α in A549 cells and in lung of BALB/c mice but not in HELF cells. Treatment with Lificiguat (YC-1), HIF-1α inhibitor, or CoCl2, HIF-1α inducer, could alter Cr(VI)-induced autophagy, glycolysis, and cell growth in A549 cells but not in HELF cells, validating the involvement of HIF-1α in these effects of Cr(VI) in A549 cells. Co-treatments of pcATG4B with YC-1, or siATG4B with CoCl2 demonstrated the role of HIF-1α / autophagy axis in inducing glycolysis and cell growth in A549 cells. In HELF cells, however, only autophagy but not HIF-1α played a role in inducing glycolysis. The protein level of p53 was significantly lower in A549 cells than in HELF cells. RITA, a p53 inducer, attenuated Cr(VI)-induced HIF-1α and LC3-II in A549 cells, suggesting that p53 might be the mechanism underlying the different effects of Cr(VI) on HIF-1α in A549 and HELF cells. Thus, p53-dependent HIF-1α / autophagy-mediated glycolysis plays a role in facilitating Cr(VI)-induced carcinogenesis.

HSP90 inhibition suppresses tumor glycolytic flux to potentiate the therapeutic efficacy of radiotherapy for head and neck cancer

Glycolytic metabolism may account for antitumor immunity failure. Pyruvate kinase M2 (PKM2) and platelet phosphofructokinase (PFKP), two key enzymes involved in the glycolytic pathway, are hyperactivated in head and neck squamous cell carcinoma (HNSCC). Using ganetespib as a drug model for heat shock protein 90 (HSP90) inhibition and combining results from clinical trials and animal treatment, we demonstrated that HSP90 inhibition leads to a blockade of glycolytic flux in HNSCC cells by simultaneously suppressing PKM2 and PFKP at both the transcriptional and posttranslational levels. Down-regulation of tumor glycolysis facilitates tumor infiltration of cytotoxic T cells via suppression of glycolysis-dependent interleukin-8 signaling. The addition of ganetespib to radiation attenuates radiation-induced up-regulation of PKM2 and PFKP and potentiates T cell-mediated antitumor immunity, resulting in a more potent antitumor effect than either treatment alone, providing a molecular basis for exploring the combination of HSP90 inhibitors with radiotherapy to improve outcomes for patients with HNSCC.

Blocking tumor-platelet crosstalk to prevent tumor metastasis via reprograming glycolysis using biomimetic membrane-hybridized liposomes

Activated platelets promote tumor progression and metastasis through active interactions with cancer cells, especially in promoting epithelial-mesenchymal transition (EMT) of tumor cells and shedding tumor cells into the blood. Blocking platelet-tumor cell interactions can be a potential strategy to inhibit tumor metastasis. Platelet activation requires energy produced from aerobic glycolysis. Based on this, we propose a platelet suppression strategy by reprogramming glucose metabolism of platelets, which has an advantage over conventional antiplatelet treatment that has a risk of serious hemorrhage. We develop a biomimetic delivery system using platelet membrane-hybridized liposomes (PM-Lipo) for codelivery of quercetin and shikonin to simultaneously inhibit lactate transporter MCT-4 and a glycolytic enzyme PKM2 for achieving metabolic reprogramming of platelets and suppressing platelet activation. Notably, PM-Lipo can also inhibit glycolysis in cancer cells, which actually takes "two-birds-one-stone" action. Consequently, the platelet-tumor cell interactions are inhibited. Moreover, PM-Lipo can bind with circulating tumor cells and reduce their seeding in the premetastatic microenvironment. The in vivo studies further demonstrated that PM-Lipo can effectively suppress primary tumor growth and reduce lung metastasis without affecting inherited functions of platelets. Reprogramming glycolysis of platelets can remodel the tumor immune microenvironment, including suppression of Treg and stimulation of CTLs.

Comprehensive characterization and preclinical assessment of an imidazopyridine-based anticancer lead molecule

Imidazopyridine scaffold holds significant pharmacological importance in the treatment of cancer. An in-house synthesized imidazopyridine-based molecule was found to have promising anticancer activity against breast cancer, lung cancer, and colon cancer. The molecule is an inhibitor of pyruvate kinase M2, the enzyme that elevates tumor growth, metastasis and chemoresistance by directly controlling tumor cell metabolism. Screening of the physicochemical properties of any lead molecules is essential to avoid failure in late-stage drug development. In this research, the physicochemical properties of the molecule including log P, log D, pKa, and plasma protein binding were assessed to check its drug-likeness. Plasma and metabolic stability of the molecule were also evaluated. Moreover, pharmacokinetic profiles of the lead molecule in Sprague-Dawley rats and in vitro metabolite identification studies were also performed. Finally, an in silico software, Pro-Tox-II, was used to predict toxicity of the molecule and its metabolites. Log P, Log D (pH 7.4), pKa, and plasma protein binding of the molecule were found to be 2.03%, 2.42%, 10.4%, and 98%, respectively. The molecule was stable in plasma and metabolic conditions. A total of nine new metabolites were identified and characterized. Cmax and t½ of this molecule were found to be 4016 ± 313.95 ng/mL and 9.57 ± 3.05 h, respectively. Based on the previously reported study and this finding, the molecule can be considered as a promising anticancer lead with potential drug-likeness properties. Further preclinical and clinical drug discovery studies may be initiated in continuation of this study in search of a potential anticancer lead.

PKM2 is a Novel Osteoporosis-Associated Protein in Chinese

                       Purpose:Osteoporosis is characterized by low bone mineral density (BMD) and high risk of osteoporotic fracture (OF). Peripheral blood monocytes (PBM) can differentiate into osteoclasts to resorb bone. This study was to identify PBM-expressed proteins significant for osteoporosis in Chinese Han elderly population (>65 years), and focused on two phenotypes of osteoporosis: low BMD and OF.

METHODS

Label-free quantitative proteomics was employed to profile PBM proteome and to identify differentially expressed proteins (DEPs) between OF (N=27) vs. non-fractured (NF, N=24) subjects and between low BMD (N=12) vs. high BMD (N=12) subjects in women. Western blotting (WB) was conducted to validate differential expression, and ELISA to evaluate translational value for secretory protein of interest.

RESULTS

We discovered 59 DEPs with fold change (FC)>1.3 (P<1×10-5), and validated the significant up-regulation of pyruvate kinase isozyme 2 (PKM2) with osteoporosis (P<0.001). PKM2 protein upregulation with OF was replicated with PBM in men (P=0.04). Plasma PKM2 protein level was significantly elevated with OF in an independent sample (N=100, FC=1.68, P=0.01). Pursuant functional assays showed that extracellular PKM2 protein supplement not only promoted monocyte trans-endothelial migration, growth, and osteoclast differentiation (marker gene expression), but also inhibited osteoblast growth, differentiation (ALP gene expression), and activity.

CONCLUSION

The above findings suggest that PKM2 protein is a novel osteoporosis-associated functional protein in Chinese Han elderly population. It may serve as a risk biomarker and drug target for osteoporosis.

Activation of GPR3-β-arrestin2-PKM2 pathway in Kupffer cells stimulates glycolysis and inhibits obesity and liver pathogenesis

Kupffer cells are liver resident macrophages and play critical role in fatty liver disease, yet the underlying mechanisms remain unclear. Here, we show that activation of G-protein coupled receptor 3 (GPR3) in Kupffer cells stimulates glycolysis and protects mice from obesity and fatty liver disease. GPR3 activation induces a rapid increase in glycolysis via formation of complexes between β-arrestin2 and key glycolytic enzymes as well as sustained increase in glycolysis through transcription of glycolytic genes. In mice, GPR3 activation in Kupffer cells results in enhanced glycolysis, reduced inflammation and inhibition of high-fat diet induced obesity and liver pathogenesis. In human fatty liver biopsies, GPR3 activation increases expression of glycolytic genes and reduces expression of inflammatory genes in a population of disease-associated macrophages. These findings identify GPR3 activation as a pivotal mechanism for metabolic reprogramming of Kupffer cells and as a potential approach for treating fatty liver disease.

Apatinib weakens proliferation, migration, invasion, and angiogenesis of thyroid cancer cells through downregulating pyruvate kinase M2

Thyroid cancer (TC) is the most frequent malignancy of the endocrine system. Apatinib, as an anti-angiogenic agent, has been applied in the therapy of several cancers. However, the function and mechanism of Apatinib in TC have not been clearly elucidated. After processing with Apatinib alone or combined PKM2 overexpression plasmids, cell proliferation, migration, and invasion were analyzed by EdU staining, CCK-8, wound healing, and Transwell. Meanwhile. HUVECs were incubated with the conditioned medium prepared from cell culture medium, and tube formation and VEGFR2 expression in HUVECs were examined using tube formation and immunofluorescence (IF) assays. Besides, we established a nude mouse xenograft model by lentivirus-mediated PKM2 shRNAs, and tested the growth of tumors; the pathological structure was analyzed with H&E staining. And the expressions of N-cadherin, Vimentin, E-cadherin, PKM2, VEGFA, VEGFR2, and Ki67 were determined by immunohistochemistry or Western blot. Apatinib could prominently suppress proliferation, migration, invasion, and HUVEC tube formation in SW579 and TPC-1 cells. Besides, we discovered that Apatinib had a significant inhibitory role on the expression of pyruvate kinase M2 (PKM2) in TC cells. And PKM2 overexpression also could notably reverse Apatinib-mediated inhibition of TC progression. Moreover, PKM2 shRNAs were applied to TC xenografts, resulting in significant reduction in tumor volume and suppression of angiogenesis-related protein expression. In summary, Apatinib has a regulatory role in TC progression, and Apatinib can block cancer cell angiogenesis by downregulating PKM2. This will provide a theoretical basis for therapy of TC.

Silencing PKM2 Attenuates Brain Injury Induced by Status Epilepticus by Inhibiting the AKT/mTOR Pathway and the NLRP3 Inflammasome

PKM2 is a glycolytic pyruvate kinase isoenzyme, and its role in neurological diseases has been published. However, the role and mechanism of PKM2 in the process of status epilepticus have not been reported. The purpose of this study is to explore the role and mechanism of PKM2 in epilepsy. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were used to explore the expression of PKM2 in cells. Enzyme-linked immunosorbent assay kits were used to evaluate the level of inflammatory factors. An epilepsy model was established by intraperitoneal injection of lithium chloride in rats. Various behavioural assays were conducted to explore the learning ability and cognitive level of rats. PKM2 expression was upregulated in Mg2+-induced hippocampal neurons. PKM2 inhibition ameliorated Mg2+-induced hippocampal neuronal inflammation and reduced neuronal apoptosis. In addition, PKM2 silencing inhibited the metabolic dysfunction of Mg2+-induced hippocampal neurons. Subsequent experiments showed that the Akt/mTOR pathway and NLRP3 inflammasome are involved in PKM2-mediated neuronal regulation. More importantly, PKM2 inhibition could alleviate status epilepticus in rats. PKM2 inhibition attenuates Mg2+-induced hippocampal neuronal inflammation, apoptosis and metabolic dysfunction and improves the cognitive ability of rats. Therefore, PKM2 may be an important target for epilepsy treatment.

The upregulation of miR-3945 in CD14+ monocytes is the risk factor for cardiovascular disease

Patients with type 1 diabetes (T1DM) show an increased risk of cardiovascular disease. Bioinformatics analysis revealed that it is characterized by changes in the function of CD14+ mononuclear macrophages. The current study was to explore the potential relationship between the miR-3845/TRIM35/PKM2 and abnormal polarization of mononuclear macrophages. Using bioinformatics to analyze the gene expression of mononuclear macrophages. The polarization of macrophages was analyzed using flow cytometry, and the expression changes of TRIM35/PKM2 were analyzed using Western blot, luciferase activity assay, and co-immunoprecipitation. Database analysis showed that T1DM patients showed an abnormal increase of miR-3945 in CD14+ monocyte macrophages. miR-3945 targets TRIM35 to release PKM2 to cytometry, and PKM2 causes M1-like polarization of mononuclear macrophages. Database analysis showed that miR-3945 was abnormally upregulated in CD14+ monocytes in T1DM patients. miR-3945 upregulates the expression of PKM2 in the cytoplasm by targeting TRIM35, which leads to M1 polarization of macrophages.

Aerobic glycolysis is the predominant means of glucose metabolism in neuronal somata, which protects against oxidative damage

It is generally thought that under basal conditions, neurons produce ATP mainly through mitochondrial oxidative phosphorylation (OXPHOS), and glycolytic activity only predominates when neurons are activated and need to meet higher energy demands. However, it remains unknown whether there are differences in glucose metabolism between neuronal somata and axon terminals. Here, we demonstrated that neuronal somata perform higher levels of aerobic glycolysis and lower levels of OXPHOS than terminals, both during basal and activated states. We found that the glycolytic enzyme pyruvate kinase 2 (PKM2) is localized predominantly in the somata rather than in the terminals. Deletion of Pkm2 in mice results in a switch from aerobic glycolysis to OXPHOS in neuronal somata, leading to oxidative damage and progressive loss of dopaminergic neurons. Our findings update the conventional view that neurons uniformly use OXPHOS under basal conditions and highlight the important role of somatic aerobic glycolysis in maintaining antioxidant capacity.

Pyruvate kinase M2 (PKM-2) expression and prognostic significance in glioblastoma patients

PURPOSE

Pyruvate kinase M2 (PKM2) is a key enzyme that catalyzes the irreversible and final step of glycolysis. It is closely associated with cancer development and progression. The relationship between PKM2 and prognosis in glioblastoma (GB) patients is unknown. The aim of this study was to measure PKM2 expression and evaluate its effect on prognosis in GB patients.

METHODS

Patients who underwent radiotherapy (RT) for glioblastoma between 2010 and 2021 were evaluated immunohistochemically. A single pathologist evaluated pathology specimens of all patients. The intensity and extent of staining of tumor cells were scored. Patients were categorized as low and high PKM2.

RESULTS

A total of 119 patients were evaluated. While 80.7% of the cases had a low score, 19.3% had a high PKM2 score. It was observed that the group with high PKM2 expression had lower performance, received more hypofractionated RT and received adjuvant chemotherapy (CT) less frequently. Median overall survival (OS) was 15.77 months in the low PKM2 expression group and 6.50 months in the high PKM2 group. In univariate analyses, PKM2 expression, age, performance status, type of surgery, RT scheme, and concurrent and adjuvant CT were prognostic factors in predicting OS. In multivariate analyses, PKM2 expression, type of surgery, RT scheme and receiving adjuvant CT were prognostic factors for OS.

CONCLUSION

PKM2 is an independent prognostic factor for survival and is associated with poor prognosis in GBM patients treated with radiotherapy. It may be a potential therapeutic target for anticancer therapy.

Endothelial Cell-Derived Lactate Triggers Bone Mesenchymal Stem Cell Histone Lactylation to Attenuate Osteoporosis

Blood vessels play a role in osteogenesis and osteoporosis; however, the role of vascular metabolism in these processes remains unclear. The present study finds that ovariectomized mice exhibit reduced blood vessel density in the bone and reduced expression of the endothelial glycolytic regulator pyruvate kinase M2 (PKM2). Endothelial cell (EC)-specific deletion of Pkm2 impairs osteogenesis and worsens osteoporosis in mice. This is attributed to the impaired ability of bone mesenchymal stem cells (BMSCs) to differentiate into osteoblasts. Mechanistically, EC-specific deletion of Pkm2 reduces serum lactate levels secreted by ECs, which affect histone lactylation in BMSCs. Using joint CUT&Tag and RNA sequencing analyses, collagen type I alpha 2 chain (COL1A2), cartilage oligomeric matrix protein (COMP), ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), and transcription factor 7 like 2 (TCF7L2) as osteogenic genes regulated by histone H3K18la lactylation are identified. PKM2 overexpression in ECs, lactate addition, and exercise restore the phenotype of endothelial PKM2-deficient mice. Furthermore, serum metabolomics indicate that patients with osteoporosis have relatively low lactate levels. Additionally, histone lactylation and related osteogenic genes of BMSCs are downregulated in patients with osteoporosis. In conclusion, glycolysis in ECs fuels BMSC differentiation into osteoblasts through histone lactylation, and exercise partially ameliorates osteoporosis by increasing serum lactate levels.

Application of recombinant human pyruvate kinase in recombinase polymerase amplification

Recombinase polymerase amplification (RPA) is an isothermal DNA amplification reaction at around 41°C using recombinase (Rec), single-stranded DNA-binding protein (SSB), strand-displacing DNA polymerase (Pol), and an ATP-regenerating enzyme. In this study, we attempted to use pyruvate kinase instead of creatine kinase (CK) that has been consistently used as an ATP-regenerating enzyme in RPA. Human pyruvate kinase M1 (PKM) was expressed in Escherichia coli and purified from the cells. RPA with PKM was performed at 41°C with the in vitro synthesized urease subunit β (ureB) DNA from Ureaplasma parvum serovar 3 as a standard DNA. The optimal concentrations of PKM and phosphoenolpyruvate were 20 ng/μL and 10 mM, respectively. The RPA reaction with PKM was more sensitive than that with CK. PKM exhibited higher thermostability than CK, suggesting that the RPA reagents with PKM are preferable to those with CK for onsite use.

The Warburg Effect Explained: Integration of Enhanced Glycolysis with Heterogeneous Mitochondria to Promote Cancer Cell Proliferation

The Warburg effect is the long-standing riddle of cancer biology. How does aerobic glycolysis, inefficient in producing ATP, confer a growth advantage to cancer cells? A new evaluation of a large set of literature findings covering the Warburg effect and its yeast counterpart, the Crabtree effect, led to an innovative working hypothesis presented here. It holds that enhanced glycolysis partially inactivates oxidative phosphorylation to induce functional rewiring of a set of TCA cycle enzymes to generate new non-canonical metabolic pathways that sustain faster growth rates. The hypothesis has been structured by constructing two metabolic maps, one for cancer metabolism and the other for the yeast Crabtree effect. New lines of investigation, suggested by these maps, are discussed as instrumental in leading toward a better understanding of cancer biology in order to allow the development of more efficient metabolism-targeted anticancer drugs.

The Complex Effects of PKM2 and PKM2:IP3R Disruption on Intracellular Ca2+ Handling and Cellular Functions

Pyruvate kinase M (PKM) 2 was described to interact with the inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) and suppress its activity. To further investigate the physiological importance of the PKM2:IP3R interaction, we developed and characterized HeLa PKM2 knockout (KO) cells. In the HeLa PKM2 KO cells, the release of Ca2+ to the cytosol appears to be more sensitive to low agonist concentrations than in HeLa wild-type (WT) cells. However, upon an identical IP3-induced Ca2+ release, Ca2+ uptake in the mitochondria is decreased in HeLa PKM2 KO cells, which may be explained by the smaller number of contact sites between the ER and the mitochondria. Furthermore, in HeLa PKM2 KO cells, mitochondria are more numerous, though they are smaller and less branched and have a hyperpolarized membrane potential. TAT-D5SD, a cell-permeable peptide representing a sequence derived from IP3R1 that can disrupt the PKM2:IP3R interaction, induces Ca2+ release into the cytosol and Ca2+ uptake into mitochondria in both HeLa WT and PKM2 KO cells. Moreover, TAT-D5SD induced apoptosis in HeLa WT and PKM2 KO cells but not in HeLa cells completely devoid of IP3Rs. These results indicate that PKM2 separately regulates cytosolic and mitochondrial Ca2+ handling and that the cytotoxic effect of TAT-D5SD depends on IP3R activity but not on PKM2. However, the tyrosine kinase Lck, which also interacts with the D5SD sequence, is expressed neither in HeLa WT nor PKM2 KO cells, and we can also exclude a role for PKM1, which is upregulated in HeLa PKM2 KO cells, indicating that the TAT-D5SD peptide has a more complex mode of action than anticipated.

Circular RNA P4HB promotes glycolysis and tumor progression by binding with PKM2 in lung adenocarcinoma

BACKGROUND

Emerging evidence indicates that circular RNAs (circRNAs) play vital roles in tumor progression, including lung adenocarcinomas (LUAD). However, the mechanisms by which circRNAs promote the progression of LUAD still require further investigation.

METHODS

Quantitative real-time PCR was performed to detect the expression of circP4HB in LUAD tissues and cells. Then, Kaplan-Meier analysis was used to determine the prognostic value of circP4HB expression. We employed RNA pull-down, RNA immunoprecipitation, mass spectrometry, cells fraction, glucose consumption, lactate production, pyruvate kinase M2 (PKM2) activity, and macrophage polarization assays to uncover the underlying mechanisms of circP4HB in LUAD.

RESULTS

We found that circP4HB is upregulated in LUAD tissues and correlated with advanced TNM stages and lymph node metastasis. LUAD patients with high circP4HB expression had poor prognoses. Functionally, circP4HB promoted LUAD progression in vivo and in vitro. Upregulated circP4HB increased glucose consumption, lactate production and accelerated aerobic glycolysis in LUAD cells. Mechanically, circP4HB mainly accumulated in the cytoplasm of LUAD cells and bound with PKM2 and subsequently upregulating PKM2 enzymatic activity by increasing its tetramer formation. Additionally, circP4HB promoted M2 macrophage phenotype shift via targeting PKM2. Finally, rescue assays further confirmed that circP4HB could promote LUAD cell progression through its interaction with PKM2.

CONCLUSION

These results demonstrate that circP4HB could promote LUAD progression, indicating circP4HB might be a potential therapeutic target of LUAD.

Research progress of hyperthermia in tumor therapy by influencing metabolic reprogramming of tumor cells

Cellular metabolic reprogramming is an important feature of malignant tumors. Metabolic reprogramming causes changes in the levels or types of specific metabolites inside and outside the cell, which affects tumorigenesis and progression by influencing gene expression, the cellular state, and the tumor microenvironment. During tumorigenesis, a series of changes in the glucose metabolism, fatty acid metabolism, amino acid metabolism, and cholesterol metabolism of tumor cells occur, which are involved in the process of cellular carcinogenesis and constitute part of the underlying mechanisms of tumor formation. Hyperthermia, as one of the main therapeutic tools for malignant tumors, has obvious effects on tumor cell metabolism. In this paper, we will combine the latest research progress in the field of cellular metabolic reprogramming and focus on the current experimental research and clinical treatment of hyperthermia in cellular metabolic reprogramming to discuss the feasibility of cellular metabolic reprogramming-related mechanisms guiding hyperthermia in malignant tumor treatment, so as to provide more ideas for hyperthermia to treat malignant tumors through the direction of cellular metabolic reprogramming.

The potential role of reprogrammed glucose metabolism: an emerging actionable codependent target in thyroid cancer

Although the incidence of thyroid cancer is increasing year by year, most patients, especially those with differentiated thyroid cancer, can usually be cured with surgery, radioactive iodine, and thyroid-stimulating hormone suppression. However, treatment options for patients with poorly differentiated thyroid cancers or radioiodine-refractory thyroid cancer have historically been limited. Altered energy metabolism is one of the hallmarks of cancer and a well-documented feature in thyroid cancer. In a hypoxic environment with extreme nutrient deficiencies resulting from uncontrolled growth, thyroid cancer cells utilize "metabolic reprogramming" to satisfy their energy demand and support malignant behaviors such as metastasis. This review summarizes past and recent advances in our understanding of the reprogramming of glucose metabolism in thyroid cancer cells, which we expect will yield new therapeutic approaches for patients with special pathological types of thyroid cancer by targeting reprogrammed glucose metabolism.

Reinventing the Penumbra - the Emerging Clockwork of a Multi-modal Mechanistic Paradigm

The concept of the ischemic penumbra was originally defined as the area around a necrotic stroke core and seen as the tissue at imminent risk of further damage. Today, the penumbra is generally considered as time-sensitive hypoperfused brain tissue with decreased oxygen and glucose availability, salvageable tissue as treated by intervention, and the potential target for neuroprotection in focal stroke. The original concept entailed electrical failure and potassium release but one short of neuronal cell death and was based on experimental stroke models, later confirmed in clinical imaging studies. However, even though the basic mechanisms have translated well, conferring brain protection, and improving neurological outcome after stroke based on the pathophysiological mechanisms in the penumbra has yet to be achieved. Recent findings shape the modern understanding of the penumbra revealing a plethora of molecular and cellular pathophysiological mechanisms. We now propose a new model of the penumbra, one which we hope will lay the foundation for future translational success. We focus on the availability of glucose, the brain's central source of energy, and bioenergetic failure as core pathophysiological concepts. We discuss the relation of mitochondrial function in different cell types to bioenergetics and apoptotic cell death mechanisms, autophagy, and neuroinflammation, to glucose metabolism in what is a dynamic ischemic penumbra.

Metabolic interventions combined with CTLA-4 and PD-1/PD-L1 blockade for the treatment of tumors: mechanisms and strategies

Immunotherapies based on immune checkpoint blockade (ICB) have significantly improved patient outcomes and offered new approaches to cancer therapy over the past decade. To date, immune checkpoint inhibitors (ICIs) of CTLA-4 and PD-1/PD-L1 represent the main class of immunotherapy. Blockade of CTLA-4 and PD-1/PD-L1 has shown remarkable efficacy in several specific types of cancers, however, a large subset of refractory patients presents poor responsiveness to ICB therapy; and the underlying mechanism remains elusive. Recently, numerous studies have revealed that metabolic reprogramming of tumor cells restrains immune responses by remodeling the tumor microenvironment (TME) with various products of metabolism, and combination therapies involving metabolic inhibitors and ICIs provide new approaches to cancer therapy. Nevertheless, a systematic summary is lacking regarding the manner by which different targetable metabolic pathways regulate immune checkpoints to overcome ICI resistance. Here, we demonstrate the generalized mechanism of targeting cancer metabolism at three crucial immune checkpoints (CTLA-4, PD-1, and PD-L1) to influence ICB therapy and propose potential combined immunotherapeutic strategies co-targeting tumor metabolic pathways and immune checkpoints.

Pyruvate Kinase Activity Regulates Cystine Starvation Induced Ferroptosis through Malic Enzyme 1 in Pancreatic Cancer Cells

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with high mortality and limited efficacious therapeutic options. PDAC cells undergo metabolic alterations to survive within a nutrient-depleted tumor microenvironment. One critical metabolic shift in PDAC cells occurs through altered isoform expression of the glycolytic enzyme, pyruvate kinase (PK). Pancreatic cancer cells preferentially upregulate pyruvate kinase muscle isoform 2 isoform (PKM2). PKM2 expression reprograms many metabolic pathways, but little is known about its impact on cystine metabolism. Cystine metabolism is critical for supporting survival through its role in defense against ferroptosis, a non-apoptotic iron-dependent form of cell death characterized by unchecked lipid peroxidation. To improve our understanding of the role of PKM2 in cystine metabolism and ferroptosis in PDAC, we generated PKM2 knockout (KO) human PDAC cells. Fascinatingly, PKM2KO cells demonstrate a remarkable resistance to cystine starvation mediated ferroptosis. This resistance to ferroptosis is caused by decreased PK activity, rather than an isoform-specific effect. We further utilized stable isotope tracing to evaluate the impact of glucose and glutamine reprogramming in PKM2KO cells. PKM2KO cells depend on glutamine metabolism to support antioxidant defenses against lipid peroxidation, primarily by increased glutamine flux through the malate aspartate shuttle and utilization of ME1 to produce NADPH. Ferroptosis can be synergistically induced by the combination of PKM2 activation and inhibition of the cystine/glutamate antiporter in vitro. Proof-of-concept in vivo experiments demonstrate the efficacy of this mechanism as a novel treatment strategy for PDAC.

ESRRG-PKM2 axis reprograms metabolism to suppress esophageal squamous carcinoma progression and enhance anti-PD-1 therapy efficacy

BACKGROUND

Glycolysis under normoxic conditions, known as the Warburg effect, confers a selective advantage for the survival and proliferation of many tumors. In this study, we investigated the role of estrogen-related receptor gamma (ESRRG) in metabolic reprogramming in esophageal squamous cell carcinoma (ESCC).

METHODS

Bioinformatics analysis indicated that ESRRG expression was decreased in ESCC tissue and associated with poor clinical outcomes. We also examined the effects of altered ESRRG expression on the proliferation and metabolic reprogramming of ESCC cells. We explored the impact of ESRRG on Pyruvate kinase M2 (PKM2) expression and malignant behavior in ESCC.

RESULTS

Our study revealed the inhibitory effects of ESRRG on the growth, tumorigenesis, and glycolysis activity of ESCC cells, which were mediated by the downregulation of PKM2 expression. We further demonstrated that ESRRG directly interacts with the PKM2 promoter to inhibit its activity in ESCC. Notably, the ESRRG-specific agonist, DY131, inhibited ESCC cell proliferation and glycolysis activity by modulating genes in the glycolysis pathway. Moreover, we verified that DY131 exhibits enhanced activity as an immune checkpoint inhibitor, considering the significance of the ESRRG-PKM2 axis in the lactate regulation of ESCC cells.

CONCLUSION

Our findings provide novel insights into the role of ESRRG-PKM2 signaling in regulating ESCC cell metabolism and immune checkpoint regulation. Additionally, we suggest that DY131 holds promise as a promising therapeutic agent for ESCC treatment.

Development of [18F]DASA-10 for enhanced imaging of pyruvate kinase M2

PURPOSE

The aim of this study was to develop a positron emission tomography (PET) radiotracer for measuring pyruvate kinase M2 (PKM2) with improved physicochemical and pharmacokinetic properties compared to [18F]DASA-23.

EXPERIMENTAL DESIGN

First, we synthesized [18F]DASA-10 and tested its uptake and retention compared to [18F]DASA-23 in human and mouse glioma cell lines. We then confirmed the specificity of [18F]DASA-10 by transiently modulating the expression of PKM2 in DU145 and HeLa cells. Next, we determined [18F]DASA-10 pharmacokinetics in healthy nude mice using PET imaging and subsequently assessed the ability of [18F]DASA-10 versus [18F]DASA-23 to enable in vivo detection of intracranial gliomas in syngeneic C6 rat models of glioma.

RESULTS

[18F]DASA-10 demonstrated excellent cellular uptake and retention with values significantly higher than [18F]DASA-23 in all cell lines and timepoints investigated. [18F]DASA-10 showed a 73 % and 65 % reduced uptake respectively in DU145 and HeLa cells treated with PKM2 siRNA as compared to control siRNA treated cells. [18F]DASA-10 showed favorable biodistribution and pharmacokinetic properties and a significantly improved tumor-to-brain ratio in rat C6 glioma models relative to [18F]DASA-23 (3.2 ± 0.8 versus 1.6 ± 0.3, p = 0.01).

CONCLUSION

[18F]DASA-10 is a new PET radiotracer for molecular imaging of PKM2 with potential to overcome the prior limitations observed with [18F]DASA-23. [18F]DASA-10 shows promise for clinical translation to enable imaging of brain malignancies owing to its low background signal in the healthy brain.

Activation of pyruvate kinase as therapeutic option for rare hemolytic anemias: Shedding new light on an old enzyme

Novel developments in therapies for various hereditary hemolytic anemias reflect the pivotal role of pyruvate kinase (PK), a key enzyme of glycolysis, in red blood cell (RBC) health. Without PK catalyzing one of the final steps of the Embden-Meyerhof pathway, there is no net yield of adenosine triphosphate (ATP) during glycolysis, the sole source of energy production required for proper RBC function and survival. In hereditary hemolytic anemias, RBC health is compromised and therefore lifespan is shortened. Although our knowledge on glycolysis in general and PK function in particular is solid, recent advances in genetic, molecular, biochemical, and metabolic aspects of hereditary anemias have improved our understanding of these diseases. These advances provide a rationale for targeting PK as therapeutic option in hereditary hemolytic anemias other than PK deficiency. This review summarizes the knowledge, rationale, (pre)clinical trials, and future advances of PK activators for this important group of rare diseases.

USP4 promotes the proliferation and glucose metabolism of gastric cancer cells by upregulating PKM2

BACKGROUND

The pyruvate kinase enzyme PKM2 catalyzes the final step in glycolysis and converts phosphoenolpyruvate (PEP) to pyruvate. PKM2 is often overexpressed in cancer and plays a role in the Warburg effect. The expression of PKM2 can be regulated at different levels. While it has been proven that PKM2 can be regulated by ubiquitination, little is known about its de-ubiquitination regulation.

METHODS

Immunoprecipitation was applied to identify the PKM2 interaction protein and to determine the interaction region between PKM2 and USP4. Immunofluorescence was performed to determine the cellular localization of USP4 and PKM2. The regulation of PKM2 by USP4 was examined by western blot and ubiquitination assay. MTT assays, glucose uptake, and lactate production were performed to analyze the biological effects of USP4 in gastric cancer cells.

RESULTS

USP4 interacts with PKM2 and catalyzes the de-ubiquitination of PKM2. Overexpression of USP4 promotes cell proliferation, glucose uptake, and lactate production in gastric cancer cells. Knockdown of USP4 reduces PKM2 levels and results in a reduction in cell proliferation and the glycolysis rate.

CONCLUSIONS

USP4 plays a tumor-promoting role in gastric cancer cells by regulating PKM2.

Review of possible mechanisms of radiotherapy resistance in cervical cancer

Radiotherapy is one of the main treatments for cervical cancer. Early cervical cancer is usually considered postoperative radiotherapy alone. Radiotherapy combined with cisplatin is the standard treatment for locally advanced cervical cancer (LACC), but sometimes the disease will relapse within a short time after the end of treatment. Tumor recurrence is usually related to the inherent radiation resistance of the tumor, mainly involving cell proliferation, apoptosis, DNA repair, tumor microenvironment, tumor metabolism, and stem cells. In the past few decades, the mechanism of radiotherapy resistance of cervical cancer has been extensively studied, but due to its complex process, the specific mechanism of radiotherapy resistance of cervical cancer is still not fully understood. In this review, we discuss the current status of radiotherapy resistance in cervical cancer and the possible mechanisms of radiotherapy resistance, and provide favorable therapeutic targets for improving radiotherapy sensitivity. In conclusion, this article describes the importance of understanding the pathway and target of radioresistance for cervical cancer to promote the development of effective radiotherapy sensitizers.

Recent advances microRNAs and metabolic reprogramming in colorectal cancer research

Colorectal cancer (CRC) is a cancer with the highest incidence and mortality. Alteration of gene expression is the main pathophysiological mechanism of CRC, which results in disturbed signaling pathways and cellular metabolic processes. MicroRNAs are involved in almost all pathophysiological processes and are correlative with colorectal cancer metabolism, proliferation, and chemotherapy resistance. Metabolic reprogramming, an important feature of cancer, is strongly correlative with the development and prognosis of cancers, including colorectal cancer. MicroRNAs can target enzymes involved in metabolic processes, thus playing a regulatory role in tumor metabolism. The disorder of the signaling pathway is another characteristic of tumor, which induces the occurrence and proliferation of tumors, and is closely correlative with the prognosis and chemotherapy resistance of tumor patients. MicroRNAs can target the components of the signaling pathways to regulate their transduction. Understanding the function of microRNAs in the occurrence and proliferation of CRC provides novel insights into the optimal treatment strategies, prognosis, and development of diagnosis in CRC. This article reviews the relationship between CRC and microRNA expression and hopes to provide new options for the diagnosis and treatment of CRC.

Glycolysis in Chronic Liver Diseases: Mechanistic Insights and Therapeutic Opportunities

Chronic liver diseases (CLDs) cover a spectrum of liver diseases, ranging from nonalcoholic fatty liver disease to liver cancer, representing a growing epidemic worldwide with high unmet medical needs. Glycolysis is a conservative and rigorous process that converts glucose into pyruvate and sustains cells with the energy and intermediate products required for diverse biological activities. However, abnormalities in glycolytic flux during CLD development accelerate the disease progression. Aerobic glycolysis is a hallmark of liver cancer and is responsible for a broad range of oncogenic functions including proliferation, invasion, metastasis, angiogenesis, immune escape, and drug resistance. Recently, the non-neoplastic role of aerobic glycolysis in immune activation and inflammatory disorders, especially CLD, has attracted increasing attention. Several key mediators of aerobic glycolysis, including HIF-1α and pyruvate kinase M2 (PKM2), are upregulated during steatohepatitis and liver fibrosis. The pharmacological inhibition or ablation of PKM2 effectively attenuates hepatic inflammation and CLD progression. In this review, we particularly focused on the glycolytic and non-glycolytic roles of PKM2 in the progression of CLD, highlighting the translational potential of a glycolysis-centric therapeutic approach in combating CLD.

Adrenomedullin induces cisplatin chemoresistance in ovarian cancer through reprogramming of glucose metabolism

Background and Objectives

The metabolic network of cancer cells has been reprogrammed - relying more on aerobic glycolysis to gain energy, which is an important reason for drug resistance. Expression of adrenomedullin (ADM) in ovarian cancer tissues is related to resistance to platinum-based drugs. In view of this, we intended to investigate the correlation between ADM and glucose metabolism reprogramming of tumor cells to clarify the possible mechanism of ADM-induced ovarian cancer cisplatin resistance through glucose metabolism reprogramming.

Methods

Epithelial ovarian cancer (EOC) cell viability and apoptosis were determined. Different gene expression and protein levels were detected by real-time revere transcription polymerase chain reaction and western blotting. Oxygen consumption rate (OCR) and extracellular acidification rates (ECARs) were measured.

Results

ADM expression was upregulated in cisplatin-resistant EOC cells. ADM attenuated cisplatin-inhibited cell survival and cisplatin-induced apoptosis in sensitive EOC cells; knockdown of ADM enhanced cisplatin chemosensitivity of cisplatin-resistant EOC cells. ADM enhanced glycolysis in cisplatin-sensitive EOC cells; knockdown of ADM significantly inhibited glycolysis in cisplatin-resistant EOC cells. ADM significantly upregulated pyruvate kinase isozyme type M2 (PKM2) protein level, the key enzyme during glycolysis; PKM2 inhibitor significantly abolished the ADM-improved cell survival and ADM-inhibited apoptosis.

Conclusion

ADM promoted proliferation and inhibited apoptosis of ovarian cancer cells through reprogramming of glucose metabolism, so as to promote cisplatin resistance. The study is expected to identify multidrug resistance markers of ovarian cancer and provide a target for the prevention and treatment of ovarian cancer, which is important for clinical translational research.

Glucose metabolism reprogramming promotes immune escape of hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a complex process that plays an important role in its progression. Abnormal glucose metabolism in HCC cells can meet the nutrients required for the occurrence and development of liver cancer, better adapt to changes in the surrounding microenvironment, and escape the attack of the immune system on the tumor. There is a close relationship between reprogramming of glucose metabolism and immune escape. This article reviews the current status and progress of glucose metabolism reprogramming in promoting immune escape in liver cancer, aiming to provide new strategies for clinical immunotherapy of liver cancer.

Tumor metabolism rewiring in epithelial ovarian cancer

The mortality rate of epithelial ovarian cancer (EOC) remains the first in malignant tumors of the female reproductive system. The characteristics of rapid proliferation, extensive implanted metastasis, and treatment resistance of cancer cells require an extensive metabolism rewiring during the progression of cancer development. EOC cells satisfy their rapid proliferation through the rewiring of perception, uptake, utilization, and regulation of glucose, lipids, and amino acids. Further, complete implanted metastasis by acquiring a superior advantage in microenvironment nutrients competing. Lastly, success evolves under the treatment stress of chemotherapy and targets therapy. Understanding the above metabolic characteristics of EOCs helps to find new methods of its treatment.

Anti-tumor effects of novel alkannin derivatives with potent selectivity on comprehensive analysis

BACKGROUND

Therapeutic approaches based on glycolysis and energy metabolism of tumor cells are new promising strategies for the treatment of cancer. Currently, researches on the inhibition of pyruvate kinase M2, a key rate limiting enzyme in glycolysis, have been corroborated as an effective cancer therapy. Alkannin is a potent pyruvate kinase M2 inhibitor. However, its non-selective cytotoxicity has affected its subsequent clinical application. Thus, it needs to be structurally modified to develop novel derivatives with high selectivity.

PURPOSE

Our study aimed to ameliorate the toxicity of alkannin through structural modification and elucidate the mechanism of the superior derivative 23 in lung cancer therapy.

METHODS

On the basis of the principle of collocation, different amino acids and oxygen-containing heterocycles were introduced into the hydroxyl group of the alkannin side chain. We examined the cell viability of all derivatives on three tumor cells (HepG2, A549 and HCT116) and two normal cells (L02 and MDCK) by MTT assay. Besides, the effect of derivative 23 on the morphology of A549 cells as observed by Giemsa and DAPI staining, respectively. Flow cytometry was performed to assess the effects of derivative 23 on apoptosis and cell cycle arrest. To further assess the effect of derivative 23 on the Pyruvate kinase M2 in glycolysis, an enzyme activity assay and western blot assay were performed. Finally, in vivo the antitumor activity and safety of the derivative 23 were evaluated by using Lewis mouse lung cancer xenograft model.

RESULTS

Twenty-three novel alkannin derivatives were designed and synthesized to improve the cytotoxicity selectivity. Among these derivatives, derivative 23 showed the highest cytotoxicity selectivity between cancer and normal cells. The anti-proliferative activity of derivative 23 on A549 cells (IC₅₀ = 1.67 ± 0.34 μM) was 10-fold higher than L02 cells (IC₅₀ = 16.77 ± 1.44 μM) and 5-fold higher than MDCK cells (IC₅₀ = 9.23 ± 0.29 μM) respectively. Subsequently, fluorescent staining and flow cytometric analysis showed that derivative 23 was able to induce apoptosis of A549 cells and arrest the cell cycle in the G0/G1 phase. In addition, the mechanistic studies suggested derivative 23 was an inhibitor of pyruvate kinase; it could regulate glycolysis by inhibiting the activation of the phosphorylation of PKM2/STAT3 signaling pathway. Furthermore, studies in vivo demonstrated derivative 23 significantly inhibited the growth of xenograft tumor.

CONCLUSION

In this study, alkannin selectivity is reported to be significantly improved following structural modification, and derivative 23 is first shown to be able to inhibit lung cancer growth via the PKM2/STAT3 phosphorylation signaling pathway in vitro, indicating the potential value of derivative 23 in treating lung cancer.

The "sweet" path to cancer: focus on cellular glucose metabolism

The hypoxia-inducible factor-1α (HIF-1α), a key player in the adaptive regulation of energy metabolism, and the M2 isoform of the glycolytic enzyme pyruvate kinase (PKM2), a critical regulator of glucose consumption, are the main drivers of the metabolic rewiring in cancer cells. The use of glycolysis rather than oxidative phosphorylation, even in the presence of oxygen (i.e., Warburg effect or aerobic glycolysis), is a major metabolic hallmark of cancer. Aerobic glycolysis is also important for the immune system, which is involved in both metabolic disorders development and tumorigenesis. More recently, metabolic changes resembling the Warburg effect have been described in diabetes mellitus (DM). Scientists from different disciplines are looking for ways to interfere with these cellular metabolic rearrangements and reverse the pathological processes underlying their disease of interest. As cancer is overtaking cardiovascular disease as the leading cause of excess death in DM, and biological links between DM and cancer are incompletely understood, cellular glucose metabolism may be a promising field to explore in search of connections between cardiometabolic and cancer diseases. In this mini-review, we present the state-of-the-art on the role of the Warburg effect, HIF-1α, and PKM2 in cancer, inflammation, and DM to encourage multidisciplinary research to advance fundamental understanding in biology and pathways implicated in the link between DM and cancer.

Simultaneous suppression of PKM2 and PHGDH elicits synergistic anti-cancer effect in NSCLC

Metabolic reprogramming is a hallmark of human cancer. Cancer cells exhibit enhanced glycolysis, which allows glycolytic intermediates to be diverted into several other biosynthetic pathways, such as serine synthesis. Here, we explored the anti-cancer effects of the pyruvate kinase (PK) M2 inhibitor PKM2-IN-1 alone or in combination with the phosphoglycerate dehydrogenase (PHGDH) inhibitor NCT-503 in human NSCLC A549 cells in vitro and in vivo. PKM2-IN-1 inhibited proliferation and induced cell cycle arrest and apoptosis, with increased glycolytic intermediate 3-phosphoglycerate (3-PG) level and PHGDH expression. The combination of PKM2-IN-1 and NCT-503 further suppressed cancer cell proliferation and induced G2/M phase arrest, accompanied by the reduction of ATP, activation of AMPK and inhibition of its downstream mTOR and p70S6K, upregulation of p53 and p21, as well as downregulation of cyclin B1 and cdc2. In addition, combined treatment triggered ROS-dependent apoptosis by affecting the intrinsic Bcl-2/caspase-3/PARP pathway. Moreover, the combination suppressed glucose transporter type 1 (GLUT1) expression. In vivo, co-administration of PKM2-IN-1 and NCT-503 significantly inhibited A549 tumor growth. Taken together, PKM2-IN-1 in combination with NCT-503 exhibited remarkable anti-cancer effects through induction of G2/M cell cycle arrest and apoptosis, in which the metabolic stress induced ATP reduction and ROS augmented DNA damage might be involved. These results suggest that the combination of PKM2-IN-1 and NCT-503 might be a potential strategy for the therapy of lung cancer.

S-lactoyl modification of KEAP1 by a reactive glycolytic metabolite activates NRF2 signaling

KEAP1 (Kelch-like ECH-associated protein), a cytoplasmic repressor of the oxidative stress responsive transcription factor Nuclear factor erythroid 2-related factor 2 (NRF2), senses the presence of electrophilic agents by modification of its sensor cysteine residues. In addition to xenobiotics, several reactive metabolites have been shown to covalently modify key cysteines on KEAP1, although the full repertoire of these molecules and their respective modifications remain undefined. Here, we report the discovery of sAKZ692, a small molecule identified by high-throughput screening that stimulates NRF2 transcriptional activity in cells by inhibiting the glycolytic enzyme pyruvate kinase. sAKZ692 treatment promotes the buildup of glyceraldehyde 3-phosphate, a metabolite which leads to S-lactate modification of cysteine sensor residues of KEAP1, resulting in NRF2-dependent transcription. This work identifies a posttranslational modification of cysteine derived from a reactive central carbon metabolite and helps further define the complex relationship between metabolism and the oxidative stress-sensing machinery of the cell.

TFEB inhibition induces melanoma shut-down by blocking the cell cycle and rewiring metabolism

Melanomas are characterised by accelerated cell proliferation and metabolic reprogramming resulting from the contemporary dysregulation of the MAPK pathway, glycolysis and the tricarboxylic acid (TCA) cycle. Here, we suggest that the oncogenic transcription factor EB (TFEB), a key regulator of lysosomal biogenesis and function, controls melanoma tumour growth through a transcriptional programme targeting ERK1/2 activity and glucose, glutamine and cholesterol metabolism. Mechanistically, TFEB binds and negatively regulates the promoter of DUSP-1, which dephosphorylates ERK1/2. In melanoma cells, TFEB silencing correlates with ERK1/2 dephosphorylation at the activation-related p-Thr185 and p-Tyr187 residues. The decreased ERK1/2 activity synergises with TFEB control of CDK4 expression, resulting in cell proliferation blockade. Simultaneously, TFEB rewires metabolism, influencing glycolysis, glucose and glutamine uptake, and cholesterol synthesis. In TFEB-silenced melanoma cells, cholesterol synthesis is impaired, and the uptake of glucose and glutamine is inhibited, leading to a reduction in glycolysis, glutaminolysis and oxidative phosphorylation. Moreover, the reduction in TFEB level induces reverses TCA cycle, leading to fatty acid production. A syngeneic BRAFV600E melanoma model recapitulated the in vitro study results, showing that TFEB silencing sustains the reduction in tumour growth, increase in DUSP-1 level and inhibition of ERK1/2 action, suggesting a pivotal role for TFEB in maintaining proliferative melanoma cell behaviour and the operational metabolic pathways necessary for meeting the high energy demands of melanoma cells.

A PKM2 inhibitor induces apoptosis and autophagy through JAK2 in human oral squamous cell carcinoma cells

The enzyme pyruvate kinase M2 (PKM2) is involved in glycolysis, which plays an important role in the regulation of tumor progression. In this study, we investigated the anti-tumor activity of N-(4-(3-(3-(methylamino)-3-oxopropyl)-5-(4'-(prop-2-yn-1-yloxy)-[1,1'-biphenyl]-4-yl)-1H-pyrazol-1-yl)phenyl)propiolamide (MTP), a PKM2 inhibitor, in oral squamous cell carcinoma (OSCC) cells. Our results showed that MTP inhibited cell growth with IC50 values of 0.59 μM and 0.78 μM in SCC2095 and HSC3 OSCC cells, respectively. MTP induced caspase-dependent apoptosis, which was associated with the modulation of PKM2 and oncogenic biomarkers epidermal growth factor receptor and β-catenin. In addition, MTP increased the generation of reactive oxygen species (ROS) and modulated the expression of autophagic gene products, including LC3B-II and p62. Western blotting showed that MTP inhibited Janus kinase 2 (JAK2) signaling, and JAK2 overexpression partially reversed MTP-mediated cytotoxicity. Taken together, these data indicate the potential use of MTP as a therapeutic agent for OSCC.

The interplay between non-coding RNAs and alternative splicing: from regulatory mechanism to therapeutic implications in cancer

Alternative splicing (AS) is a common and conserved process in eukaryotic gene regulation. It occurs in approximately 95% of multi-exon genes, greatly enriching the complexity and diversity of mRNAs and proteins. Recent studies have found that in addition to coding RNAs, non-coding RNAs (ncRNAs) are also inextricably linked with AS. Multiple different types of ncRNAs are generated by AS of precursor long non-coding (pre-lncRNAs) or precursor messenger RNAs (pre-mRNAs). Furthermore, ncRNAs, as a novel class of regulators, can participate in AS regulation by interacting with the cis-acting elements or trans-acting factors. Several studies have implicated abnormal expression of ncRNAs and ncRNA-related AS events in the initiation, progression, and therapy resistance in various types of cancers. Therefore, owing to their roles in mediating drug resistance, ncRNAs, AS-related factors and AS-related novel antigens may serve as promising therapeutic targets in cancer treatment. In this review, we summarize the interaction between ncRNAs and AS processes, emphasizing their great influences on cancer, especially on chemoresistance, and highlighting their potential values in clinical treatment.

OBHS Drives Abnormal Glycometabolis Reprogramming via GLUT1 in Breast Cancer

Due to the poor metabolic conditions fomenting the emergence of the Warburg effect (WE) phenotype, abnormal glycometabolism has become a unique and fundamental research topic in the field of tumor biology. Moreover, hyperglycemia and hyperinsulinism are associated with poor outcomes in patients with breast cancer. However, there are a few studies on anticancer drugs targeting glycometabolism in breast cancer. We hypothesized that Oxabicycloheptene sulfonate (OBHS), a class of compounds that function as selective estrogen receptor modulators, may hold potential in a therapy for breast cancer glycometabolism. Here, we evaluated concentrations of glucose, glucose transporters, lactate, 40 metabolic intermediates, and glycolytic enzymes using an enzyme-linked immunosorbent assay, Western blotting, and targeted metabolomic analysis in, in vitro and in vivo breast cancer models. OBHS significantly inhibited the expression of glucose transporter 1 (GLUT1) via PI3K/Akt signaling pathway to suppress breast cancer progression and proliferation. Following an investigation of the modulatory effect of OBHS on breast cancer cells, we found that OBHS suppressed the glucose phosphorylation and oxidative phosphorylation of glycolytic enzymes, leading to the decreased biological synthesis of ATP. This study was novel in highlighting the role of OBHS in the remodeling of tumor glycometabolism in breast cancer, and this is worth further investigation of breast cancer in clinical trials.