Function Of Pyruvate Kinase M2 Research Articles

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.

Recent Advances on PKM2 Inhibitors and Activators in Cancer Applications.

Metabolic reprogramming of cells, from the normal mode of glucose metabolism named glycolysis, is a pivotal characteristic of impending cancerous cells. Pyruvate kinase M2 (PKM2), an important enzyme that catalyzes the final rate-limiting stage during glycolysis, is highly expressed in numerous types of tumors and aids in development of favorable conditions for the survival of tumor cells. Increasing evidence has suggested that PKM2 is one of promising targets for innovative drug discovery, especially for the developments of antitumor therapeutics. Herein, we systematically summarize the recent advancement on PKM2 modulators including inhibitors and activators in cancer applications. We also discussed the classifications of pyruvate kinases in mammals and the biological functions of PKM2 in this review. We do hope that this review would provide a comprehensive understanding of the current research on PKM2 modulators, which may benefit the development of more potent PKM2-related drug candidates to treat PKM2-associated diseases including cancers in future.

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

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

PKM2 promotes glioma progression by mediating CTNNB1 expression

ABSTRACT Background Glioma is a common intracranial tumor, exhibiting a high degree of aggressiveness and invasiveness. Pyruvate kinase M2 (PKM2) is overexpressed in glioma tissues. However, the biological role of PKM2 in glioma is unclear. Methods The qRT-PCR, CCK-8, Transwell, flow cytometry detection, western blot assays, ELISA assay, and pyruvate kinase activity assays were performed in glioma cells transfected with PKM2 shRNA to explore the function of PKM2 in glioma progression. Then, STRING website was used to predict the proteins that interacted with PKM2, and Co-IP assay was conducted to further validate their interaction. Subsequently, the above experiments were performed again to find the effect of catenin beta 1 (CTNNB1) overexpression on PKM2-deficient glioma cells. The transplanted tumor models were also established to further validate our findings. Results PKM2 was up-regulated in glioma cells and tissues. After inhibiting PKM2, the proliferation, migration, glycolysis, and EMT of glioma cells were significantly decreased, and the proportion of apoptosis was increased. The prediction results of STRING website showed that CTNNB1 and PKM2 had the highest interaction score. The correlation between CTNNB1 and PKM2 was further confirmed by Co-IP test. PKM2 knockdown suppressed glioma cell proliferation, migration, glycolysis, and EMT, while CTNNB1 overexpression rescued these inhibitory effects. Correspondingly, PKM2 knockdown inhibited glioma growth in vivo. Conclusion In summary, these findings indicated that PKM2 promotes glioma progression by mediating CTNNB1 expression, providing a possible molecular marker for the clinical management of gliomas.

The role of PKM2 in cancer progression and its structural and biological basis.

Pyruvate kinase M2 (PKM2), a subtype of pyruvate kinase (PK), has been shown to play an important role in the development of cancer. It regulates the last step of glycolytic pathway. PKM2 has both pyruvate kinase and protein kinase activity, and the conversion of these two functions of PKM2 depends on the mutual change of dimer and tetramer. The dimerization of PKM2 can promote the proliferation and growth of tumor cells, so inhibiting the dimerization of PKM2 is essential to curing cancer. The aggregation of PKM2 is regulated by both endogenous and exogenous cofactors as well as post-translational modification (PTM). Although there are many studies on the different aggregation of PKM2 in the process of tumor development, there are few summaries in recent years. In this review, we first introduce the role of PKM2 in various biological processes of tumor growth. Then, we summarize the aggregation regulation mechanism of PKM2 by various endogenous cofactors such as Fructose-1, 6-diphosphate (FBP), various amino acids, and post-translational modification (PTMs). Finally, the related inhibitors and agonists of PKM2 are summarized to provide reference for regulating PKM2 aggregation in the treatment of cancer in the future.

Non-metabolic enzyme function of PKM2 in hepatocellular carcinoma: A review.

Hepatocellular carcinoma (HCC) is one of the most malignant tumors with the highest incidence and mortality in the world, causing a serious burden on society. Pyruvate kinase M2 (PKM2) is one of the principal metabolic enzymes involved in glycolysis. Studies have shown that PKM2 is highly expressed in HCC and can be translocated to the nucleus, where it interacts with various transcription factors and proteins such as hypoxia-inducible factor-1α, sterol regulatory element-binding protein 1a, signal transducer and activator of transcription 3, nuclear factor erythroid 2-like 2 and histone H3, exerting non-metabolic enzyme functions to regulate the cell cycle, proliferation, apoptosis, immune escape, migration, and invasion, as well as HCC angiogenesis and tumor microenvironment. This review is focused on the recent progress of PKM2 interacting with various transcription factors and proteins affecting the onset and development of HCC, as well as natural drugs and noncoding RNA impacting diverse biological functions of liver cancer cells by regulating PKM2 non-metabolic enzyme functions, thereby providing valuable directions for the prognosis improvement and molecular targeted therapy of HCC in the future.

The metabolic function of pyruvate kinase M2 regulates reactive oxygen species production and microbial killing by neutrophils

Neutrophils rely predominantly on glycolytic metabolism for their biological functions, including reactive oxygen species (ROS) production. Although pyruvate kinase M2 (PKM2) is a glycolytic enzyme known to be involved in metabolic reprogramming and gene transcription in many immune cell types, its role in neutrophils remains poorly understood. Here, we report that PKM2 regulates ROS production and microbial killing by neutrophils. Zymosan-activated neutrophils showed increased cytoplasmic expression of PKM2. Pharmacological inhibition or genetic deficiency of PKM2 in neutrophils reduced ROS production and Staphylococcus aureus killing in vitro. In addition, this also resulted in phosphoenolpyruvate (PEP) accumulation and decreased dihydroxyacetone phosphate (DHAP) production, which is required for de novo synthesis of diacylglycerol (DAG) from glycolysis. In vivo, PKM2 deficiency in myeloid cells impaired the control of infection with Staphylococcus aureus. Our results fill the gap in the current knowledge of the importance of lower glycolysis for ROS production in neutrophils, highlighting the role of PKM2 in regulating the DHAP and DAG synthesis to promote ROS production in neutrophils.

Sulforaphane diminishes moonlighting of pyruvate kinase M2 and interleukin 1β expression in M1 (LPS) macrophages.

Murine macrophages activated by the Toll-like receptor 4 agonist lipopolysaccharide (LPS) polarize to the M1 type by inducing proinflammatory marker proteins and changing their energy metabolism to increased aerobic glycolysis and reduced respiration. We here show that the aliphatic isothiocyanate sulforaphane (Sfn) diminishes M1 marker expression (IL-1β, IL-6, TNF-α, iNOS, NO, and ROS) and leads to highly energetic cells characterized by both high glycolytic and high respiratory activity as assessed by extracellular flux analysis. Focusing on a potential connection between high glycolytic activity and low IL-1β expression in M1 (LPS/Sfn) macrophages, we reveal that Sfn impedes the moonlighting function of pyruvate kinase M2 (PKM2) in M1 macrophages. Sfn limits mono/dimerization and nuclear residence of PKM2 accompanied by reduced HIF-1α levels, Stat3 phosphorylation at tyrosine 705, and IL-1β expression while preserving high levels of cytosolic PKM2 tetramer with high glycolytic enzyme activity. Sfn prevents glutathionylation of PKM2 in LPS-stimulated macrophages which may account for the reduced loss of PKM2 tetramer. Overall, we uncover PKM2 as a novel affected hub within the anti-inflammatory activity profile of Sfn.

LncCCAT1 interaction protein PKM2 upregulates SREBP2 phosphorylation to promote osteosarcoma tumorigenesis by enhancing the Warburg effect and lipogenesis.

Pyruvate kinase M2 (PKM2) plays an important role in the consumption of glucose and the production of lactic acid, the striking feature of cancer metabolism. The association of PKM2 with osteosarcoma (OS) has been reported but its role in OS has yet to be elucidated. To study this, PKM2-bound RNAs in HeLa cells, a type of cancer cells widely used in the study of molecular function and mechanism, were obtained. Peak calling analysis revealed that PKM2 binds to long noncoding RNAs (lncRNAs), which are associated with cancer pathogenesis and development. Validation of the PKM2-lncRNA interaction in the human OS cell line revealed that lncRNA colon cancer associated transcript-1 (lncCCAT1) interacted with PKM2, which upregulated the phosphorylation of sterol regulatory element-binding protein 2 (SREBP2). These factors promoted the Warburg effect, lipogenesis, and OS cell growth. PKM2 appears to be a key regulator in OS by binding to lncCCAT1. This further extends the biological functions of PKM2 in tumorigenesis and makes it a novel potential therapeutic for OS.

FSTL1 promotes liver fibrosis by reprogramming macrophage function through modulating the intracellular function of PKM2

ObjectiveFollistatin-like protein 1 (FSTL1) is widely recognised as a secreted glycoprotein, but its role in modulating macrophage-related inflammation during liver fibrosis has not been documented. Herein, we aimed to characterise...

Non-metabolic functions of pyruvate kinase M2: PKM2 in tumorigenesis and therapy resistance.

Cancer is the disease of uncontrollably dividing cells in the body. As cancer cells proliferate at higher rates, they need more energy in a short time necessitating deregulation of energy-generating pathways for their benefit. Although oxidative phosphorylation generates more energy from a glucose molecule, cancer cells have a tendency to enhance aerobic glycolysis by consuming more glucose and producing lactate as a by-product even if oxygen is present. In addition to the generation of rapid energy to fulfill their increasing demands, this strategy also provides the use of glucose metabolites such as lactate as a source for the synthesis of anabolic molecules, such as nucleotides, amino acids, and lipids during the rapid phase of the proliferation. Pyruvate kinase M2 (PKM2) is an isoform of pyruvate kinase, which mediates the balancing of energy generation mechanisms during the anabolic and catabolic events. Due to its vital role in glycolysis, PKM2 has been investigated to target cancer cell metabolism for several years. However, recent studies demonstrate that PKM2 may also promote cancer progression by regulating core steps in metastasis such as migration, angiogenesis, and stemness. Of note, it is estimated that 90% of cancer-related deaths are due to metastasis. This review is intended to summarize the recent advances in the non-metabolic roles of PKM2 in cancer progression and to indicate its potential uses for the development of new treatment strategies.

Lactylation of PKM2 Suppresses Inflammatory Metabolic Adaptation in Pro-inflammatory Macrophages.

Emerging evidence suggests that metabolic adaptation is a vital hallmark and prerequisite for macrophage phenotype transition. Pyruvate kinase M2 (PKM2) is an essential molecular determinant of metabolic adaptions in pro-inflammatory macrophages. Post-translational modifications play a central role in the regulation of PKM2. However, doubt remains on whether lactylation in PKM2 exists and how lactylation modulates the function of PKM2. For the first time, our study reports that lactate inhibits the Warburg effect by activating PKM2, promoting the transition of pro-inflammatory macrophages towards a reparative phenotype. We identify PKM2 as a lactylation substrate and confirm that lactylation occurs mainly at the K62 site. We find that lactate increases the lactylation level of PKM2, which inhibits its tetramer-to-dimer transition, promoting its pyruvate kinase activity and reducing nuclear distribution. In short, our study reports a novel post-translational modification type in PKM2 and clarifies its potential role in regulating inflammatory metabolic adaptation in pro-inflammatory macrophages.

Lipid metabolism: new twists to the Yin and Yang of PKM2 in cancer.

While canonical and non-canonical functions of pyruvate kinase M2 (PKM2) are recognized to mediate often-opposing roles in cancer, its contribution to cellular and systemic fatty acid homeostasis remains poorly understood. A new study by Liu etal (2021) uncovers ER transmembrane protein TMEM33 as a novel target of PKM2, which is essential for regulation of cancer cell cholesterol metabolism. These findings highlight the diversity of tissue-specific functions of PKM2 and potential implications for cancer treatment.

Non-Metabolic Functions of PKM2 Contribute to Cervical Cancer Cell Proliferation Induced by the HPV16 E7 Oncoprotein

Pyruvate kinase M2 (PKM2) mainly catalyzes glycolysis, but it also exerts non-glycolytic functions in several cancers. While it has been shown to interact with the human papillomavirus 16 (HPV16) E7 oncoprotein, the functional significance of PKM2 in HPV-associated cervical cancer has been elusive. Here, we show that HPV16 E7 increased the expression of PKM2 in cervical cancer cells. TCGA data analyses revealed a higher level of PKM2 in HPV+ than HPV− cervical cancers and a worse prognosis for patients with high PKM2 expression. Functionally, we demonstrate that shRNA-mediated PKM2 knockdown decreased the proliferation of HPV+ SiHa cervical cancer cells. PKM2 knockdown also inhibited the E7-induced proliferation of cervical cancer cells. ML265 activating the pyruvate kinase function of PKM2 inhibited cell cycle progression and colony formation. ML265 treatments decreased phosphorylation of PKM2 at the Y105 position that has been associated with non-glycolytic functions. On the contrary, HPV16 E7 increased the PKM2 phosphorylation. Our results indicate that E7 increases PKM2 expression and activates a non-glycolytic function of PKM2 to promote cervical cancer cell proliferation.

HDAC8-dependent deacetylation of PKM2 directs nuclear localization and glycolysis to promote proliferation in hepatocellular carcinoma

Pyruvate kinase M2 (PKM2) is not only a key rate-limiting enzyme that guides glycolysis, but also acts as a non-metabolic protein in regulating gene transcription. In recent years, a series of studies have confirmed that post-translational modification has become an important mechanism for regulating the function of PKM2, which in turn affects tumorigenesis. In this study, we found that K62 residues were deacetylated, which is related to the prognosis of HCC. Further studies indicate that HDAC8 binds and deacetylates the K62 residue of PKM2. Mechanistically, K62 deacetylation facilitate PKM2 transport into the nucleus and bind β-catenin, thereby promoting CCND1 gene transcription and cell cycle progression. In addition, the deacetylation of K62 affects the enzyme activity of PKM2 and the flux of glucose metabolism. Therefore, these results suggest that HDAC8 / PKM2 signaling may become a new target for the treatment of HCC.

Pyruvate kinase M2 (PKM2) in cancer and cancer therapeutics.

Pyruvate kinase M2 (PKM2), a key rate-limiting enzyme of glycolysis, is a critical regulator in tumor metabolism. PKM2 has been demonstrated to overexpressed in various cancers and promoted proliferation and metastasis of tumor cells. The errant expression of PKM2 has inspired people to investigate the function of PKM2 and the therapeutic potential in cancer. In addition, some studies have shown that the upregulation of PKM2 in tumor tissues is associated with the altered expression of lncRNAs and the poor survival. Therefore, researchers have begun to unravel the specific molecular mechanisms of lncRNA-mediated PKM2 expression in cancer metabolism. As the tumor microenvironment (TME) is essential in tumor development, it is necessary to identify the role of PKM2 in TME. In this review, we will introduce the role of PKM2 in different cancers as well as TME, and summarize the molecular mechanism of PKM2-related lncRNAs in cancer metabolism. We expect that this work will lead to a better understanding of the molecular mechanisms of PKM2 that may help in developing therapeutic strategies in clinic for researchers.

Inhibiting Protein Kinase Activity of Pyruvate Kinase M2 by SIRT2 Deacetylase Attenuates Psoriasis

Signal transducer and activator of transcription 3 (STAT3) is crucial for the pathogenesis of psoriasis. Studies describe pleiotropic roles for a glycolytic enzyme pyruvate kinase M2 (PKM2) as a nuclear kinase of STAT3. However, little is known about the function of PKM2 in T helper type 17 cells in association with STAT3. In this study, we investigated whether and how SIRT2 deacetylase regulated the protein kinase function of PKM2 in T helper type 17 cell‒mediated inflammatory responses in psoriasis. Sirt2 knockout mice and wild-type littermates had psoriatic dermatitis induced by topical treatment of imiquimod or intradermal injection of recombinant IL-23. An initial downregulation of SIRT2 and an increase in PKM2 acetylation and STAT3 phosphorylation were observed in psoriasiform lesions of mice. SIRT2 directly interacted with and deacetylated PKM2 to suppress STAT3 phosphorylation. Consequently, psoriasiform skin inflammation was aggravated in Sirt2 knockout mice. Conversely, genetic re-expression of Sirt2 or pharmacological blockade of PKM2 decreased the disease severity. Flow cytometric analysis of skin tissues of Sirt2 knockout mice showed enhanced infiltration of T helper type 17 cells. Exvivo experiments showed that SIRT2 deficiency accelerated T helper type 17 cell differentiation with the concomitant production of IL-17A and IL-22. The results suggest SIRT2-mediated PKM2 deacetylation as an effective option for psoriasis therapy.

Knockdown of Pyruvate Kinase M2 Inhibits Cell Proliferation, Metabolism, and Migration in Renal Cell Carcinoma.

Emerging evidence indicates that the activity of pyruvate kinase M2 (PKM2) isoform is crucial for the survival of tumor cells. However, the molecular mechanism underlying the function of PKM2 in renal cancer is undetermined. Here, we reveal the overexpression of PKM2 in the proximal tubule of renal tumor tissues from 70 cases of patients with renal carcinoma. The functional role of PKM2 in human renal cancer cells following small-interfering RNA-mediated PKM2 knockdown, which retarded 786-O cell growth was examined. Targeting PKM2 affected the protein kinase B (AKT)/mechanistic target of the rapamycin 1 (mTOR) pathway, and downregulated the expression of glycolytic enzymes, including lactate dehydrogenase A and glucose transporter-1, and other downstream signaling key proteins. PKM2 knockdown changed glycolytic metabolism, mitochondrial function, adenosine triphosphate (ATP) level, and intracellular metabolite formation and significantly reduced 786-O cell migration and invasion. Acridine orange and monodansylcadaverine staining, immunocytochemistry, and immunoblotting analyses revealed the induction of autophagy in renal cancer cells following PKM2 knockdown. This is the first study to indicate PKM2/AKT/mTOR as an important regulatory axis mediating the changes in the metabolism of renal cancer cells.

Epigenetic regulation of the Warburg effect by H2B monoubiquitination.

Cancer cells reprogram their energy metabolic system from the mitochondrial oxidative phosphorylation (OXPHOS) pathway to a glucose-dependent aerobic glycolysis pathway. This metabolic reprogramming phenomenon is known as the Warburg effect, a significant hallmark of cancer. However, the detailed mechanisms underlying this event or triggering this reprogramming remain largely unclear. Here, we found that histone H2B monoubiquitination (H2Bub1) negatively regulates the Warburg effect and tumorigenesis in human lung cancer cells (H1299 and A549 cell lines) likely through controlling the expression of multiple mitochondrial respiratory genes, which are essential for OXPHOS. Moreover, our work also suggested that pyruvate kinase M2 (PKM2), the rate-limiting enzyme of glycolysis, can directly interact with H2B in vivo and in vitro and negatively regulate the level of H2Bub1. The inhibition of cell proliferation and nude mice xenograft of human lung cancer cells induced by PKM2 knockdown can be partially rescued through lowering H2Bub1 levels, which indicates that the oncogenic function of PKM2 is achieved, at least partially, through the control of H2Bub1. Furthermore, PKM2 and H2Bub1 levels are negatively correlated in cancer specimens. Therefore, these findings not only provide a novel mechanism triggering the Warburg effect that is mediated through an epigenetic pathway (H2Bub1) but also reveal a novel metabolic regulator (PKM2) for the epigenetic mark H2Bub1. Thus, the PKM2-H2Bub1 axis may become a promising cancer therapeutic target.

Extracellular pyruvate kinase M2 facilitates cell migration by upregulating claudin-1 expression in colon cancer cells.

Extensive studies have been reported the non-canonical functions of pyruvate kinase M2 (PKM2) as a kinase, transcriptional regulator, and even cell-to-cell communicator, emphasizing its importance in various signaling pathways. However, the role of secreted PKM2 in cancer progression and its signaling pathway is yet to be elucidated. In this study, we found that extracellular PKM2 enhanced the migration of low-metastatic, benign colon cancer cells by upregulating claudin-1 expression and internalizing it to the cytoplasm and nucleus. Knock-down of claudin-1 significantly reduced extracellular PKM2-induced cell migration. Inhibition of either protein kinase C (PKC) or epidermal growth factor receptor (EGFR) resulted in a reduction of extracellular PKM2-mediated claudin-1 expression, suggesting EGFR-PKC-claudin-1 as a signaling pathway in the extracellular PKM2-mediated tumorigenesis of colon cancer cells.