Discovery of novel naphthoquinone derivatives as inhibitors of the tumor cell specific M2 isoform of pyruvate kinase

SIRT1 improves lactate homeostasis in the brain to alleviate parkinsonism via deacetylation and inhibition of PKM2

Sirtuin 1 (SIRT1) is a histone deacetylase and plays diverse functions in various physiological events, from development to lifespan regulation. Here, in Parkinson's disease (PD) model mice, we demonstrated that SIRT1 ameliorates parkinsonism, while SIRT1 knockdown further aggravates PD phenotypes. Mechanistically, SIRT1 interacts with and deacetylates pyruvate kinase M2 (PKM2) at K135 and K206, thus leading to reduced PKM2 enzyme activity and lactate production, which eventually results in decreased glial activation in the brain. Administration of lactate in the brain recapitulates PD-like phenotypes. Furthermore, increased expression of PKM2 worsens PD symptoms, and, on the contrary, inhibition of PKM2 by shikonin or PKM2-IN-1 alleviates parkinsonism in mice. Collectively, our data indicate that excessive lactate in the brain might be involved in the progression of PD. By improving lactate homeostasis, SIRT1, together with PKM2, are likely drug targets for developing agents for the treatment of neurodegeneration in PD.

Compound 3K attenuates isoproterenol-induced cardiac hypertrophy by inhibiting pyruvate kinase M2 (PKM2) pathway

AIM

Chronic sympathetic stimulation has been identified as a primary factor in the pathogenesis of cardiac hypertrophy (CH). However, there is no appropriate treatment available for the management of CH. Recently, it has been revealed that pyruvate kinase M2 (PKM2) plays a significant role in cardiac remodeling, fibrosis, and hypertrophy. However, the therapeutic potential of selective PKM2 inhibitor has not yet been explored in cardiac hypertrophy. Thus, in the current study, we have studied the cardioprotective potential of Compound 3K, a selective PKM2 inhibitor in isoproterenol-induced CH model.

METHODS

To induce cardiac hypertrophy, male Wistar rats were subcutaneously administered isoproterenol (ISO, 5 mg/kg/day) for 14 days. Compound 3K at dosages of 2 and 4 mg/kg orally was administered to ISO-treated rats for 14 days to explore its effects on various parameters like ECG, ventricular functions, hypertrophic markers, histology, inflammation, and protein expression were performed.

RESULTS

Fourteen days administration of ISO resulted in the induction of CH, which was evidenced by alterations in ECG, ventricular dysfunctions, increase in hypertrophy markers, and fibrosis. The immunoblotting of hypertrophy heart revealed the significant rise in PKM2 and reduction in PKM1 protein expression. Treatment with Compound 3K led to downregulation of PKM2 and upregulation of PKM1 protein expression. Compound 3K showed cardioprotective effects by improving ECG, cardiac functions, hypertrophy markers, inflammation, and fibrosis. Further, it also reduced cardiac expression of PKM2-associated splicing protein, HIF-1α, and caspase-3.

CONCLUSION

Our findings suggest that Compound 3K has a potential cardioprotective effect via PKM2 inhibition in isoproterenol-induced CH.

The regulatory roles and clinical significance of glycolysis in tumor

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

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

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

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

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

Single-cell and spatial transcriptomics reveal a high glycolysis B cell and tumor-associated macrophages cluster correlated with poor prognosis and exhausted immune microenvironment in diffuse large B-cell lymphoma

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous malignancy characterized by varied responses to treatment and prognoses. Understanding the metabolic characteristics driving DLBCL progression is crucial for developing personalized therapies.

METHODS

This study utilized multiple omics technologies including single-cell transcriptomics (n = 5), bulk transcriptomics (n = 966), spatial transcriptomics (n = 10), immunohistochemistry (n = 34), multiple immunofluorescence (n = 20) and to elucidate the metabolic features of highly malignant DLBCL cells and tumor-associated macrophages (TAMs), along with their associated tumor microenvironment. Metabolic pathway analysis facilitated by scMetabolism, and integrated analysis via hdWGCNA, identified glycolysis genes correlating with malignancy, and the prognostic value of glycolysis genes (STMN1, ENO1, PKM, and CDK1) and TAMs were verified.

RESULTS

High-glycolysis malignant DLBCL tissues exhibited an immunosuppressive microenvironment characterized by abundant IFN_TAMs (CD68+CXCL10+PD-L1+) and diminished CD8+ T cell infiltration. Glycolysis genes were positively correlated with malignancy degree. IFN_TAMs exhibited high glycolysis activity and closely communicating with high-malignancy DLBCL cells identified within datasets. The glycolysis score, evaluated by seven genes, emerged as an independent prognostic factor (HR = 1.796, 95% CI: 1.077-2.995, p = 0.025 and HR = 2.631, 95% CI: 1.207-5.735, p = 0.015) along with IFN_TAMs were positively correlated with poor survival (p < 0.05) in DLBCL. Immunohistochemical validation of glycolysis markers (STMN1, ENO1, PKM, and CDK1) and multiple immunofluorescence validation of IFN_TAMs underscored their prognostic value (p < 0.05) in DLBCL.

CONCLUSIONS

This study underscores the significance of glycolysis in tumor progression and modulation of the immune microenvironment. The identified glycolysis genes and IFN_TAMs represent potential prognostic markers and therapeutic targets in DLBCL.

Babesia duncani Pyruvate Kinase Inhibitor Screening and Identification of Key Active Amino Acid Residues

Babesia duncani (B. duncani), a protozoan parasite prevalent in North America, is a significant threat for human health. Given the regulatory role of pyruvate kinase I (PyK I) in glycolytic metabolism flux and ATP generation, PyK I has been considered the target for drug intervention for a long time. In this study, B. duncani PyK I (BdPyK I) was successfully cloned, expressed, and purified. Polyclonal antibodies were confirmed to recognize the native BdPyK I protein (56 kDa) using Western blotting. AlphaFold software predicted the three-dimensional structure of BdPyK I, and molecular docking with small molecules was conducted to identify potential binding sites of inhibitor on BdPyK I. Moreover, inhibitory effects of six inhibitors (tannic acid, apigenin, shikonin, PKM2 inhibitor, rosiglitazone, and pioglitazone) on BdPyK I were examined under the optimal enzymatic conditions of 3 mM PEP and 3 mM ADP, and significant activity reduction was found. Enzyme kinetics and growth inhibition assays further confirmed the reliability of these inhibitors, with PKM2 inhibitor, tannic acid, and apigenin exhibiting the highest selectivity index as specific inhibitors for B. duncani. Subsequently, key amino acid residues were mutated in both BdPyK I and Homo sapiens pyruvate kinase I (HPyK I), and two differential amino acid residues (isoleucine and phenylalanine) were identified between HPyK I and BdPyK I through PyK activity detection experiments. These findings lay foundation for understanding the role of PyK I in the growth and development of B. duncani, providing insights for babesiosis prevention and drug development.

Functions and novel regulatory mechanisms of key glycolytic enzymes in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive vascular disease characterized by remodeling of the pulmonary vasculature and elevated pulmonary arterial pressure, ultimately leading to right heart failure and death. Despite its clinical significance, the precise molecular mechanisms driving PAH pathogenesis warrant confirmation. Compelling evidence indicates that during the development of PAH, pulmonary vascular cells exhibit a preference for energy generation through aerobic glycolysis, known as the "Warburg effect", even in well-oxygenated conditions. This metabolic shift results in imbalanced metabolism, increased proliferation, and severe pulmonary vascular remodeling. Exploring the Warburg effect and its interplay with glycolytic enzymes in the context of PAH has yielded current insights into emerging drug candidates targeting enzymes and intermediates involved in glucose metabolism. This sheds light on both opportunities and challenges in the realm of antiglycolytic therapy for PAH.

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

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

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

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

Unlocking the potential of 1,4-naphthoquinones: A comprehensive review of their anticancer properties

Cancer encompasses a group of pathologies with common characteristics, high incidence, and prevalence in all countries. Although there are treatments available for this disease, they are not always effective or safe, often failing to achieve the desired results. This is why it is necessary to continue the search for new therapies. One of the strategies for obtaining new antitumor drugs is the use of 1,4-naphthoquinone as a scaffold in synthetic or natural products with antitumor activity. This review focuses on compiling studies related to the antitumor activity of 1,4-naphthoquinone and its natural and synthetic derivatives over the last 10 years. The work describes the main natural naphthoquinones with antitumor activity and classifies the synthetic naphthoquinones based on the structural modifications made to the scaffold. Additionally, the formation of metal complexes using naphthoquinones as a ligand is considered. After a thorough review, 197 synthetic compounds with potent biological activity against cancer have been classified according to their chemical structures and their mechanisms of action have been described.

Targeting the Warburg effect: A revisited perspective from molecular mechanisms to traditional and innovative therapeutic strategies in cancer

Cancer reprogramming is an important facilitator of cancer development and survival, with tumor cells exhibiting a preference for aerobic glycolysis beyond oxidative phosphorylation, even under sufficient oxygen supply condition. This metabolic alteration, known as the Warburg effect, serves as a significant indicator of malignant tumor transformation. The Warburg effect primarily impacts cancer occurrence by influencing the aerobic glycolysis pathway in cancer cells. Key enzymes involved in this process include glucose transporters (GLUTs), HKs, PFKs, LDHs, and PKM2. Moreover, the expression of transcriptional regulatory factors and proteins, such as FOXM1, p53, NF-κB, HIF1α, and c-Myc, can also influence cancer progression. Furthermore, lncRNAs, miRNAs, and circular RNAs play a vital role in directly regulating the Warburg effect. Additionally, gene mutations, tumor microenvironment remodeling, and immune system interactions are closely associated with the Warburg effect. Notably, the development of drugs targeting the Warburg effect has exhibited promising potential in tumor treatment. This comprehensive review presents novel directions and approaches for the early diagnosis and treatment of cancer patients by conducting in-depth research and summarizing the bright prospects of targeting the Warburg effect in cancer.

Inhibition of sphingosine kinase 1 attenuates LPS-induced acute lung injury by suppressing endothelial cell pyroptosis

Acute lung injury (ALI) is a frequent complication of sepsis, with pyroptosis playing a pivotal role. Analysis of Gene Expression Omnibus (GEO) mouse sepsis datasets revealed the upregulation of sphingosine kinase 1 (SphK1) in septic mouse lung tissues, which was validated in lipopolysaccharide (LPS)-treated mice. Therefore, this study aimed to explore the potential role and underlying mechanisms of SphK1, the primary kinase responsible for catalyzing the formation of the bioactive lipid sphingosine-1-phosphat, in sepsis development. Mice received an intraperitoneal injection of SphK1 inhibitor prior to LPS administration. Mouse lung vascular endothelial cells (MLVECs) were exposed to LPS and SphK1 inhibitor. The SphK1 inhibitor mitigated ALI, as evidenced by hematoxylin and eosin (H&E) staining and the wet-to-dry (W/D) weight ratio and reduced Evans blue dye leakage. Furthermore, the SphK1 inhibitor inhibited the activation of the NOD-like receptor protein 3 inflammasome and the subsequent induction of pyroptosis both in vivo and in vitro. Intriguingly, using co-immunoprecipitation (Co-IP) combined with mass spectrometry, our findings revealed that SphK1 associates with pyruvate kinase M2 (PKM2), facilitating PKM2 phosphorylation and its nuclear translocation. TEPP-46, which has the ability to stabilize PKM2 and inhibit the phosphorylation and nuclear translocation of PKM2, markedly reduced the expression of pyroptosis-associated markers and alleviated lung injury. Concludingly, our results suggest that targeting SphK1 is a promising therapeutic strategy for ALI.

HIF-1α regulates the cell viability in radioiodine-resistant papillary thyroid carcinoma cells induced by hypoxia through PKM2/NF-κB signaling pathway

The curative treatment options for papillary thyroid cancer (PTC) encompass surgical intervention, radioactive iodine administration, and chemotherapy. However, the challenges of radioiodine (RAI) resistance, metastasis, and chemotherapy resistance remain inadequately addressed. The objective of this study was to investigate the protective role of hypoxia-inducible factor-1α (HIF-1α) in 131 I-resistant cells and a xenograft model under hypoxic conditions, as well as to explore potential mechanisms. The effects of HIF-1α on 131 I-resistant BCPAP and TPC-1 cells, as well as the xenograft model, were assessed in this study. Cell viability, migration, invasion, and apoptosis rates were measured using Cell Counting Kit-8, wound-healing, Transwell, and flow cytometry assays. Additionally, the expressions of Ki67, matrix metalloproteinase-9 (MMP-9), and pyruvate kinase M2 (PKM2) were examined using immunofluorescence or immunohistochemistry assays. Sodium iodide symporter and PKM2/NF-κBp65 relative protein levels were detected by western blot analysis. The findings of our study indicate that siHIF-1α effectively inhibits cell proliferation, cell migration, and invasion in 131 I-resistant cells under hypoxic conditions. Additionally, the treatment of siHIF-1α leads to alterations in the relative protein levels of Ki67, MMP-9, PKM2, and PKM2/NF-κBp65, both in vivo and in vitro. Notably, the effects of siHIF-1α are modified when DASA-58, an activator of PKM2, is administered. These results collectively demonstrate that siHIF-1α reduces cell viability in PTC cells and rat models, while also mediating the nuclear factor-κB (NF-κB)/PKM2 signaling pathway. Our findings provide a new rationale for further academic and clinical research on RAI-resistant PTC.

Targeting PKM2 improves the gemcitabine sensitivity of intrahepatic cholangiocarcinoma cells via inhibiting β-catenin signaling pathway

Gemcitabine is considered the standard first-line chemotherapeutic agent for patients with intrahepatic cholangiocarcinoma (ICC). However, its therapeutic efficacy is hampered by the development of chemoresistance. Pyruvate kinase M2 (PKM2), a crucial mediator of the final step in glycolysis, has been implicated in the origination and advancement of diverse malignancies. Its expression is increased in many tumor types and this may correlate with increased drug sensitivity. However, the specific effect of PKM2 on the gemcitabine sensitivity in ICC remains to be elucidated. In this research, we aimed to elucidate the role and functional significance of PKM2 in ICC, as well as the heightened susceptibility of ICC cells to gemcitabine by targeting PKM2 and the underlying molecular mechanisms. Immunohistochemical and immunofluorescence analyses revealed elevated expression of PKM2 in both tumor cells and macrophages in human ICC tissues. Reducing PKM2 levels significantly restrained the proliferation of tumor cells, impeded cell cycle advance, induced programmed cell death, and suppressed metastasis. In addition, knockdown or pharmacological inhibition of PKM2 could enhance the response of ICC cells to gemcitabine in vitro. Interestingly, conditioned medium co-culture system suggested that conditioned medium from M2 macrophages increased gemcitabine sensitivity of ICC cells. However, silencing PKM2 or pharmacological inhibition of PKM2 in M2 macrophages did not ameliorate the gemcitabine resistance mediated by M2 macrophages derived conditioned medium. Mechanistically, downregulation of PKM2 repressed the expression of β-catenin and its downstream transcriptional targets, thereby hindering the propagation of β-catenin signaling cascade. Finally, the results of the subcutaneous xenograft experiment in nude mice provided compelling evidence of a synergistic interaction between PKM2-IN-1 and gemcitabine in vivo. In summary, we reported that PKM2 may function as an advantageous target for increasing the sensitivity of ICC to gemcitabine treatment. Targeting PKM2 improves the gemcitabine sensitivity of ICC cells via inhibiting β-catenin signaling pathway.

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.

KATP channel activity and slow oscillations in pancreatic beta cells are regulated by mitochondrial ATP production

Pancreatic beta cells secrete insulin in response to plasma glucose. The ATP-sensitive potassium channel (KATP ) links glucose metabolism to islet electrical activity in these cells by responding to increased cytosolic [ATP]/[ADP]. It was recently proposed that pyruvate kinase (PK) in close proximity to beta cell KATP locally produces the ATP that inhibits KATP activity. This proposal was largely based on the observation that applying phosphoenolpyruvate (PEP) and ADP to the cytoplasmic side of excised inside-out patches inhibited KATP . To test the relative contributions of local vs. mitochondrial ATP production, we recorded KATP activity using mouse beta cells and INS-1 832/13 cells. In contrast to prior reports, we could not replicate inhibition of KATP activity by PEP + ADP. However, when the pH of the PEP solutions was not corrected for the addition of PEP, strong channel inhibition was observed as a result of the well-known action of protons to inhibit KATP . In cell-attached recordings, perifusing either a PK activator or an inhibitor had little or no effect on KATP channel closure by glucose, further suggesting that PK is not an important regulator of KATP . In contrast, addition of mitochondrial inhibitors robustly increased KATP activity. Finally, by measuring the [ATP]/[ADP] responses to imposed calcium oscillations in mouse beta cells, we found that oxidative phosphorylation could raise [ATP]/[ADP] even when ADP was at its nadir during the burst silent phase, in agreement with our mathematical model. These results indicate that ATP produced by mitochondrial oxidative phosphorylation is the primary controller of KATP in pancreatic beta cells. KEY POINTS: Phosphoenolpyruvate (PEP) plus adenosine diphosphate does not inhibit KATP activity in excised patches. PEP solutions only inhibit KATP activity if the pH is unbalanced. Modulating pyruvate kinase has minimal effects on KATP activity. Mitochondrial inhibition, in contrast, robustly potentiates KATP activity in cell-attached patches. Although the ADP level falls during the silent phase of calcium oscillations, mitochondria can still produce enough ATP via oxidative phosphorylation to close KATP . Mitochondrial oxidative phosphorylation is therefore the main source of the ATP that inhibits the KATP activity of pancreatic beta cells.

1,4-Dimethoxynaphthalene-2-methyl ('DIMON'), an oxidatively labile protecting group for synthesis of polyunsaturated lipids

A new benzyl-type protecting group (1,4-dimethoxynaphthalene-2-methyl, 'DIMON') for hydroxyl functions can be selectively removed under oxidative conditions without damaging polyunsaturated fatty acyl groups. Its application is shown by the first synthesis of an ether (plasmanyl) phospholipid containing the docosa-(4Z,7Z,10Z,13Z,16Z,19Z)-hexaenoyl group.

Small molecule inhibitors for cancer metabolism: promising prospects to be explored

BACKGROUND

Abnormal metabolism is the main hallmark of cancer, and cancer metabolism plays an important role in tumorigenesis, metastasis, and drug resistance. Therefore, studying the changes of tumor metabolic pathways is beneficial to find targets for the treatment of cancer diseases. The success of metabolism-targeted chemotherapy suggests that cancer metabolism research will provide potential new targets for the treatment of malignant tumors.

PURPOSE

The aim of this study was to systemically review recent research findings on targeted inhibitors of tumor metabolism. In addition, we summarized new insights into tumor metabolic reprogramming and discussed how to guide the exploration of new strategies for cancer-targeted therapy.

CONCLUSION

Cancer cells have shown various altered metabolic pathways, providing sufficient fuel for their survival. The combination of these pathways is considered to be a more useful method for screening multilateral pathways. Better understanding of the clinical research progress of small molecule inhibitors of potential targets of tumor metabolism will help to explore more effective cancer treatment strategies.

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.

Development of isoselenazolium chlorides as selective pyruvate kinase isoform M2 inhibitors

Alterations in cancer metabolic pathways open up an opportunity for targeted and effective elimination of tumor cells. Pyruvate kinase M2 (PKM2) is predominantly expressed in proliferating cells and plays an essential role in directing glucose metabolism in cancer. Here, we report the design of novel class of selective PKM2 inhibitors as anti-cancer agents and their mechanism of action. Compound 5c being the most active with IC₅₀ = 0.35 ± 0.07 μM, also downregulates PKM2 mRNA expression, modulates mitochondrial functionality, induces oxidative burst and is cytotoxic for various cancer types. Isoselenazolium chlorides have an unusual mechanism of PKM2 inhibition, inducing a functionally deficient tetrameric assembly, while exhibiting a competitive inhibitor character. The discovery of robust PKM2 inhibitors not only offers candidates for anticancer therapy but is also crucial for studying the role of PKM2 in 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.

Targeting hPKM2 in cancer: A bio isosteric approach for ligand design

The term cancer refers to a plethora of diseases characterized by the development of abnormal cells that divide uncontrollably and can infiltrate further proximal or distal body tissues. Each type of cancer can be defined by aggressiveness, localization, metabolism, and response to available treatments. Among the most common hallmarks of cancer is a more acidic intracellular microenvironment. Offset pH values are due to an excess of lactate and an increased hypoxia-inducible factor (HIF) expression, which leads to a hypoxic state and a metabolic shift towards glycolysis to produce adenosine-5'-triphosphate (ATP) necessary for cellular metabolism. Warburg's hypothesis underpins this concept, making glycolysis and its central enzyme pyruvate kinase (hPKM2), an ideal target for drug development. Using molecular docking and extensive molecular dynamics (MD) simulations we investigated the binding mode of phosphoenolpyruvate (PEP) inside the hPKM2 active site, and then evaluated a set of known bio-isosteric inhibitors to understand the differences caused by their substitutions on their binding mode. Ultimately, we propose a new molecular entity to hamper hPKM2, unbalance cellular energy, and possibly trigger autophagic mechanisms.

Design, Synthesis and Biological Evaluation of Quinoline-8-Sulfonamides as Inhibitors of the Tumor Cell-Specific M2 Isoform of Pyruvate Kinase: Preliminary Study

Cancer cells need to carefully regulate their metabolism to keep them growing and dividing under the influence of different nutrients and oxygen levels. Muscle isoform 2 of pyruvate kinase (PKM2) is a key glycolytic enzyme involved in the generation of ATP and is critical for cancer metabolism. PKM2 is expressed in many human tumors and is regulated by complex mechanisms that promote tumor growth and proliferation. Therefore, it is considered an attractive therapeutic target for modulating tumor metabolism. Various modulators regulate PKM2, shifting it between highly active and less active states. In the presented work, a series of 8-quinolinesulfonamide derivatives of PKM2 modulators were designed using molecular docking and molecular dynamics techniques. New compounds were synthesized using the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Compound 9a was identified in in silico studies as a potent modulator of muscle isoform 2 of pyruvate kinase. The results obtained from in vitro experiments confirmed the ability of compound 9a to reduce the intracellular pyruvate level in A549 lung cancer cells with simultaneous impact on cancer cell viability and cell-cycle phase distribution. Moreover, compound 9a exhibited more cytotoxicity on cancer cells than normal cells, pointing to high selectivity in the mode of action. These findings indicate that the introduction of another quinolinyl fragment to the modulator molecule may have a significant impact on pyruvate levels in cancer cells and provides further directions for future research to find novel analogs suitable for clinical applications in cancer treatment.

Selective Covalent Targeting of Pyruvate Kinase M2 Using Arsenous Warheads

There is growing interest in covalent targeted inhibitors in drug discovery against previously "undruggable" sites and targets. These molecules typically feature an electrophilic warhead that reacts with nucleophilic groups of protein residues, most notably the thiol group of cysteines. One main challenge in the field is to develop versatile utilizable warheads. Here, we characterize the unique features of novel arsenous warheads for reaction with thiol species in a reversible manner and further demonstrate that organoarsenic probes can be chemically tuned toward specific molecular targets by developing selective and potent inhibitors of pyruvate kinase M2 (PKM2). We show that compound 24 is a covalent and allosteric inhibitor of PKM2 and its orally bioavailable prodrug 25 exerts efficacious inhibition of PKM2-dependent tumor growth in vitro and in vivo. Our results introduce 25 and its derivatives as useful pharmacological tools and provide a general road map for targeting the protein cysteinome using arsenous warheads.

Novel Specific Pyruvate Kinase M2 Inhibitor, Compound 3h, Induces Apoptosis and Autophagy through Suppressing Akt/mTOR Signaling Pathway in LNCaP Cells

Pyruvate kinase M2 (PKM2) is a key enzyme involved in the regulation of glycolysis. Although PKM2 is overexpressed in various tumor tissues, its functional role in cancer chemotherapy remains unexplored. In this study, we investigated the anticancer activity of a new PKM2 inhibitor, compound 3h, through the cell metabolism and associated signaling pathways in prostate cancer cells. To evaluate the molecular basis of specific PKM2 inhibitors, the interactions of compounds 3h and 3K with the PKM2 protein were assessed via molecular docking. We found that, compared to compound 3K, compound 3h exhibited a higher binding affinity for PKM2. Moreover, compound 3h significantly inhibited the pyruvate kinase activity and PKM2 expression. Cytotoxicity and colony formation assays revealed the potent anticancer activity of compound 3h against LNCaP cells. Compound 3h significantly increased the apoptotic and autophagic cell death in LNCaP cells. In addition, compound 3h induced AMPK activation along with the inhibition of the mTOR/p70S6K pathway. Furthermore, compound 3h significantly inhibited glycolysis and mitochondrial respiration, as determined by analyzing the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) production. Our results revealed that compound 3h caused apoptotic and autophagic cell death in LNCaP cells by inhibiting cancer cell metabolism. Therefore, blocking glycolytic pathways using specific PKM2 inhibitors can target cancer cell metabolism in PKM2-overexpressed prostate cancer cells.

Triptolide inhibits Th17 differentiation via controlling PKM2-mediated glycolysis in rheumatoid arthritis

CONTEXT

Rheumatoid arthritis (RA) is an autoimmune disease with the aberrant differentiation of T helper 17 (Th17) cells. Pyruvate kinase M2 (PKM2), a key enzyme of glycolysis, was associated with Th17 cell differentiation.

AIM

To investigate the potential therapeutic effects of triptolide (TP) in collagen-induced arthritis (CIA) and Th17 cell differentiation, and elucidated the underlying mechanisms.

METHODS

PKM2 expression and IL-17A production in peripheral blood of RA patients were detected by RT-qPCR or ELISA. Flow cytometry and ELISA were employed to assess the effect of Th17 cell differentiation by TP. PKM2 expression and other glycolysis-related factors were detected using RT-qPCR and Western Blot. PKM2 specific inhibitor Compound 3 K was used to verify the mechanisms. Male DBA/1J mice were divided into control, model, and TP (60 μg/kg) groups to assess the anti-arthritis effect, Th17 cell differentiation and PKM2 expression.

RESULTS

PKM2 expression positively correlated with IL-17A production in RA patients. PKM2 expression was increased upon Th17 cell differentiation. Down-regulating PKM2 expression could strongly reduce Th17 cell differentiation. Molecular docking analysis predicted that TP targeted PKM2. TP treatment significantly reduced Th17 cell differentiation, PKM2 expression, pyruvate, and lactate production. In addition, compared with down-regulating PKM2 alone (Compound 3 K treatment), co-treatment with TP and Compound 3 K further significantly decreased PKM2-mediated glycolysis and Th17 cell differentiation. In CIA mice, TP repressed the PKM2-mediated glycolysis and attenuated joint inflammation.

CONCLUSION

TP inhibited Th17 cell differentiation through the inhibition of PKM2-mediated glycolysis. We highlight a novel strategy for the use of TP in RA treatment.

Rerouting the drug response: Overcoming metabolic adaptation in KRAS-mutant cancers

Mutations in guanosine triphosphatase KRAS are common in lung, colorectal, and pancreatic cancers. The constitutive activity of mutant KRAS and its downstream signaling pathways induces metabolic rewiring in tumor cells that can promote resistance to existing therapeutics. In this review, we discuss the metabolic pathways that are altered in response to treatment and those that can, in turn, alter treatment efficacy, as well as the role of metabolism in the tumor microenvironment (TME) in dictating the therapeutic response in KRAS-driven cancers. We highlight metabolic targets that may provide clinical opportunities to overcome therapeutic resistance and improve survival in patients with these aggressive cancers.

Role of Pyruvate Kinase M2 (PKM2) in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the world's leading cause of death, accounting for 32% of all fatalities. Although therapeutic agents are available for CVDs, however, most of them have significant limitations such as the time-dependency effect, hypotension, and bradycardia. To overcome the limitations of current pharmacological therapies, new molecular targets and pathways need to be identified and investigated to provide better treatment options for CVDs. Recent evidence suggested the involvement of pyruvate kinase M2 (PKM2) and targeting PKM2 by its modulators (inhibitors and activators) has shown promising results in several CVDs. PKM2 regulates gene activation in the context of apoptosis, mitosis, hypoxia, inflammation, and metabolic reprogramming. PKM2 modulators might have a significant impact on the molecular pathways involved in CVD pathogenesis. Therefore, PKM2 modulators can be one of the therapeutic options for CVDs. This review provides an insight into PKM2 involvement in various CVDs along with their therapeutic potential.

PKM2 promotes pulmonary fibrosis by stabilizing TGF-β1 receptor I and enhancing TGF-β1 signaling

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease, and the molecular mechanisms remain poorly understood. Our findings demonstrated that pyruvate kinase M2 (PKM2) promoted fibrosis progression by directly interacting with Smad7 and reinforcing transforming growth factor-β1 (TGF-β1) signaling. Total PKM2 expression and the portion of the tetrameric form elevated in lungs and fibroblasts were derived from mice with bleomycin (BLM)-induced pulmonary fibrosis. Pkm2 deletion markedly alleviated BLM-induced fibrosis progression, myofibroblast differentiation, and TGF-β1 signaling activation. Further study showed that PKM2 tetramer enhanced TGF-β1 signaling by directly binding with Smad7 on its MH2 domain, and thus interfered with the interaction between Smad7 and TGF-β type I receptor (TβR1), decreased TβR1 ubiquitination, and stabilized TβR1. Pharmacologically enhanced PKM2 tetramer by TEPP-46 promoted BLM-induced pulmonary fibrosis, while tetramer disruption by compound 3k alleviated fibrosis progression. Our results demonstrate how PKM2 regulates TGF-β1 signaling and is a key factor in fibrosis progression.

Targeting Glucose Metabolism Enzymes in Cancer Treatment: Current and Emerging Strategies

Simple Summary

Reprogramming of glucose metabolism is a hallmark of cancer and can be targeted by therapeutic agents. Some metabolism regulators, such as ivosidenib and enasidenib, have been approved for cancer treatment. Currently, more advanced and effective glucose metabolism enzyme-targeted anticancer drugs have been developed. Furthermore, some natural products have shown efficacy in killing tumor cells by regulating glucose metabolism, offering novel therapeutic opportunities in cancer. However, most of them have failed to be translated into clinical applications due to low selectivity, high toxicity, and side effects. Recent studies suggest that combining glucose metabolism modulators with chemotherapeutic drugs, immunotherapeutic drugs, and other conventional anticancer drugs may be a future direction for cancer treatment.

Abstract

Reprogramming of glucose metabolism provides sufficient energy and raw materials for the proliferation, metastasis, and immune escape of cancer cells, which is enabled by glucose metabolism-related enzymes that are abundantly expressed in a broad range of cancers. Therefore, targeting glucose metabolism enzymes has emerged as a promising strategy for anticancer drug development. Although several glucose metabolism modulators have been approved for cancer treatment in recent years, some limitations exist, such as a short half-life, poor solubility, and numerous adverse effects. With the rapid development of medicinal chemicals, more advanced and effective glucose metabolism enzyme-targeted anticancer drugs have been developed. Additionally, several studies have found that some natural products can suppress cancer progression by regulating glucose metabolism enzymes. In this review, we summarize the mechanisms underlying the reprogramming of glucose metabolism and present enzymes that could serve as therapeutic targets. In addition, we systematically review the existing drugs targeting glucose metabolism enzymes, including small-molecule modulators and natural products. Finally, the opportunities and challenges for glucose metabolism enzyme-targeted anticancer drugs are also discussed. In conclusion, combining glucose metabolism modulators with conventional anticancer drugs may be a promising cancer treatment strategy.

Cancer metabolism control by natural products: Pyruvate kinase M2 targeting therapeutics

Glycolysis is the primary source of energy for cancer growth and metastasis. The shift in metabolism from mitochondrial oxidative phosphorylation to aerobic glycolysis is called the Warburg effect. Cancer progression due to aerobic glycolysis is often associated with the activation of oncogenes or the loss of tumor suppressors. Therefore, inhibition of glycolysis is one of the effective strategies in cancer control. Pyruvate kinase M2 (PKM2) is a key glycolytic enzyme overexpressed in breast, prostate, lung, colorectal, and liver cancers. Here, we discuss published studies regarding PKM2 inhibitors from natural products that are promising drug candidates for cancer therapy. We have highlighted the potential of natural PKM2 inhibitors for various cancer types. Moreover, we encourage researchers to evaluate the combinational effects between natural and synthetic PKM2 inhibitors. Also, further high-quality studies are needed to firmly establish the clinical efficacy of natural products.

Targeting Energy Metabolism in Cancer Treatment

Cancer is the second most common cause of death worldwide after cardiovascular diseases. The development of molecular and biochemical techniques has expanded the knowledge of changes occurring in specific metabolic pathways of cancer cells. Increased aerobic glycolysis, the promotion of anaplerotic responses, and especially the dependence of cells on glutamine and fatty acid metabolism have become subjects of study. Despite many cancer treatment strategies, many patients with neoplastic diseases cannot be completely cured due to the development of resistance in cancer cells to currently used therapeutic approaches. It is now becoming a priority to develop new treatment strategies that are highly effective and have few side effects. In this review, we present the current knowledge of the enzymes involved in the different steps of glycolysis, the Krebs cycle, and the pentose phosphate pathway, and possible targeted therapies. The review also focuses on presenting the differences between cancer cells and normal cells in terms of metabolic phenotype. Knowledge of cancer cell metabolism is constantly evolving, and further research is needed to develop new strategies for anti-cancer therapies.

Positive feedback regulation of microglial glucose metabolism by histone H4 lysine 12 lactylation in Alzheimer's disease

The pro-inflammatory activation of microglia is a hallmark of Alzheimer's disease (AD), and this process involves a switch from oxidative phosphorylation (OXPHOS) toward glycolysis. Here, we show how a positive feedback loop in microglia drives AD pathogenesis, and we demonstrate that inhibiting this cycle in microglia can ameliorate Aβ burden and cognitive deficits in an AD mouse model (5XFAD). After first detecting elevated histone lactylation in brain samples from both 5XFAD mice and individuals with AD, we observed that H4K12la levels are elevated in Aβ plaque-adjacent microglia. This lactate-dependent histone modification is enriched at the promoters of glycolytic genes and activates transcription, thereby increasing glycolytic activity. Ultimately, the glycolysis/H4K12la/PKM2 positive feedback loop exacerbates microglial dysfunction in AD. Pharmacologic inhibition of PKM2 attenuated microglial activation, and microglia-specific ablation of Pkm2 improved spatial learning and memory in AD mice. Thus, our study illustrates that disruption of the positive feedback loop may be a potential therapeutic approach for the treatment of AD.

A Perspective on Medicinal Chemistry Approaches for Targeting Pyruvate Kinase M2

The allosteric regulation of pyruvate kinase M2 (PKM2) affects the switching of the PKM2 protein between the high-activity and low-activity states that allow ATP and lactate production, respectively. PKM2, in its low catalytic state (dimeric form), is chiefly active in metabolically energetic cells, including cancer cells. More recently, PKM2 has emerged as an attractive target due to its role in metabolic dysfunction and other interrelated conditions. PKM2 (dimer) activity can be inhibited by modulating PKM2 dimer-tetramer dynamics using either PKM2 inhibitors that bind at the ATP binding active site of PKM2 (dimer) or PKM2 activators that bind at the allosteric site of PKM2, thus activating PKM2 from the dimer formation to the tetrameric formation. The present perspective focuses on medicinal chemistry approaches to design and discover PKM2 inhibitors and activators and further provides a scope for the future design of compounds targeting PKM2 with better efficacy and selectivity.

Novel imidazopyrimidines-based molecules induce tetramerization of tumor pyruvate kinase M2 and exhibit potent antiproliferative profile

Discovery of novel and potent lead molecules for the specific therapeutic targets by de novo drug design is still in infancy. Here, we disclose the unprecedented development of imidazopyri(mi)dine-based tumor pyruvate kinase M2 (PKM2) modulators by subsequent link and grow strategy. The most potent modulator 15n acts as a PKM2 activator with an AC₅₀ of 90 nM, with considerable cancer cell-selectivity and membrane-permeability. NMR metabolomics studies also revealed that treatment with 15n results in diminution in lactate concentrations in MCF-7 cells. 15n binds to a previously reported site at PKM2 adjacent to the interface of two monomers. In molecular dynamics (MD) simulation studies, it was observed that 15n stabilizes the PKM2 at the dimeric interface, assisting in the formation of a biologically active tetramer conformation. 15n was also screened on MCF-7 breast cancer cell lines grown on 3-D scaffolds, and the results exhibited better anticancer potential compared to control, paving the way for future clinical studies.

Anti-cancer Research on Arnebiae Radix-derived Naphthoquinone in Recent Five Years

BACKGROUND

In recent years, many naphthoquinone compounds with anticancer activity have been identified in Arnebiae Radix, and some of them have the potential to be developed into anticancer drugs.

OBJECTIVE

This article aimed to provide a comprehensive overview of the anticancer effects of naphthoquinone compounds through a detailed review of literature and Chinese patents, and discuss their potential to be developed as anticancer drugs for clinical application.

METHODS

Research papers were collected through the databases of PubMed, Cnki and SciDirect using keyword searches "naphthoquinone compounds" and "anticancer". The keywords of "shikonin" and "shikonin derivatives" were also used in PubMed, Cnki and SciDirect databases to collect research articles. The Chinese patents were collected using the Cnki patent database.

RESULTS

Naphthoquinone compounds have been found to possess anti-cancer activity, and their modes of action are associated with inducing apoptosis, inhibiting cancer cell proliferation, promoting autophagy in cancer cells, anti-cancer angiogenesis and inhibition of cell adhesion, invasion and metastasis, inhibiting glycolysis and inhibiting DNA topoisomerase activity.

CONCLUSION

Most of the naphthoquinone compounds show effective anti-cancer activity in vitro. The structure modification of naphthoquinone aims to develop anti-cancer drugs with high efficacy and low toxicity.

Comprehensive Analysis Uncovers Prognostic and Immunogenic Characteristics of Cellular Senescence for Lung Adenocarcinoma

Cellular senescence plays a crucial role in tumorigenesis, development and immune modulation in cancers. However, to date, a robust and reliable cellular senescence-related signature and its value in clinical outcomes and immunotherapy response remain unexplored in lung adenocarcinoma (LUAD) patients. Through exploring the expression profiles of 278 cellular senescence-related genes in 936 LUAD patients, a cellular senescence-related signature (SRS) was constructed and validated as an independent prognostic predictor for LUAD patients. Notably, patients with high SRS scores exhibited upregulation of senescence-associated secretory phenotype (SASP) and an immunosuppressive phenotype. Further analysis showed that SRS combined with immune checkpoint expression or TMB served as a good predictor for patients’ clinical outcomes, and patients with low SRS scores might benefit from immunotherapy. Collectively, our findings demonstrated that SRS involved in the regulation of the tumor immune microenvironment through SASP was a robust biomarker for the immunotherapeutic response and prognosis in LUAD.

Role of PKM2-Mediated Immunometabolic Reprogramming on Development of Cytokine Storm

The cytokine storm is a marker of severity of various diseases and increased mortality. The altered metabolic profile and energy generation of immune cells affects their activation, exacerbating the cytokine storm. Currently, the emerging field of immunometabolism has highlighted the importance of specific metabolic pathways in immune regulation. The glycolytic enzyme pyruvate kinase M2 (PKM2) is a key regulator of immunometabolism and bridges metabolic and inflammatory dysfunction. This enzyme changes its conformation thus walks in different fields including metabolism and inflammation and associates with various transcription factors. This review summarizes the vital role of PKM2 in mediating immunometabolic reprogramming and its role in inducing cytokine storm, with a focus on providing references for further understanding of its pathological functions and for proposing new targets for the treatment of related diseases.

Tumor pyruvate kinase M2 modulators: a comprehensive account of activators and inhibitors as anticancer agents

Pyruvate kinase M2 (PKM2) catalyzes the conversion of phosphoenolpyruvate (PEP) to pyruvate. It plays a central role in the metabolic reprogramming of cancer cells and is expressed in most human tumors. It is essential in indiscriminate proliferation, survival, and tackling apoptosis in cancer cells. This positions PKM2 as a hot target in cancer therapy. Despite its well-known structure and several reported modulators targeting PKM2 as activators or inhibitors, a comprehensive review focusing on such modulators is lacking. Herein we summarize modulators of PKM2, the assays used to detect their potential, the preferable tense (T) and relaxed (R) states in which the enzyme resides, lacunae in existing modulators, and several strategies that may lead to effective anticancer drug development targeting PKM2.

Discovery and development of tumor glycolysis rate-limiting enzyme inhibitors

Tumor cells mainly provide necessary energy and substances for rapid cell growth through aerobic perglycolysis rather than oxidative phosphorylation. This phenomenon is called the "Warburg effect". The mechanism of glycolysis in tumor cells is more complicated, which is caused by the comprehensive regulation of multiple factors. Abnormal enzyme metabolism is one of the main influencing factors and inhibiting the three main rate-limiting enzymes in glycolysis is thought to be important strategy for cancer treatment. Therefore, numerous inhibitors of glycolysis rate-limiting enzyme have been developed in recent years, such as the latest HKII inhibitor and PKM2 inhibitor Pachymic acid (PA) and N-(4-(3-(3-(methylamino)-3-oxopropyl)-5-(4'-(trifluoromethyl)-[1,1'-biphenyl]-4-yl)-1H-pyrazol-1-yl)phenyl)propiolamide. The review focuses on source, structure-activity relationship, bioecological activity and mechanism of the three main rate-limiting enzymes inhibitors, and hopes to guide the future research on the design and synthesis of rate-limiting enzyme inhibitors.

Metabolic alterations mediated by STAT3 promotes drug persistence in CML

Leukemic stem cells (LSCs) can acquire non-mutational resistance following drug treatment leading to therapeutic failure and relapse. However, oncogene-independent mechanisms of drug persistence in LSCs are incompletely understood, which is the primary focus of this study. We integrated proteomics, transcriptomics, and metabolomics to determine the contribution of STAT3 in promoting metabolic changes in tyrosine kinase inhibitor (TKI) persistent chronic myeloid leukemia (CML) cells. Proteomic and transcriptional differences in TKI persistent CML cells revealed BCR-ABL-independent STAT3 activation in these cells. While knockout of STAT3 inhibited the CML cells from developing drug-persistence, inhibition of STAT3 using a small molecule inhibitor sensitized the persistent CML cells to TKI treatment. Interestingly, given the role of phosphorylated STAT3 as a transcription factor, it localized uniquely to genes regulating metabolic pathways in the TKI-persistent CML stem and progenitor cells. Subsequently, we observed that STAT3 dysregulated mitochondrial metabolism forcing the TKI-persistent CML cells to depend on glycolysis, unlike TKI-sensitive CML cells, which are more reliant on oxidative phosphorylation. Finally, targeting pyruvate kinase M2, a rate-limiting glycolytic enzyme, specifically eradicated the TKI-persistent CML cells. By exploring the role of STAT3 in altering metabolism, we provide critical insight into identifying potential therapeutic targets for eliminating TKI-persistent LSCs.

Specific Pyruvate Kinase M2 Inhibitor, Compound 3K, Induces Autophagic Cell Death through Disruption of the Glycolysis Pathway in Ovarian Cancer Cells

Ovarian cancer is a common cause of death among gynecological cancers. Although ovarian cancer initially responds to chemotherapy, frequent recurrence in patients remains a therapeutic challenge. Pyruvate kinase M2 (PKM2) plays a pivotal role in regulating cancer cell survival. However, its therapeutic role remains unclear. Here, we investigated the anticancer effects of compound 3K, a specific PKM2 inhibitor, on the regulation of autophagic and apoptotic pathways in SK-OV-3 (PKM2-overexpressing human ovarian adenocarcinoma cell line). The anticancer effect of compound 3K was examined using MTT and colony formation assays in SK-OV-3 cells. PKM2 expression was positively correlated with the severity of the tumor, and expression of pro-apoptotic proteins increased in SK-OV-3 cells following compound 3K treatment. Compound 3K induced AMPK activation, which was accompanied by mTOR inhibition. Additionally, this compound inhibited glycolysis, resulting in reduced proliferation of SK-OV-3 cells. Compound 3K treatment suppressed tumor progression in an in vivo xenograft model. Our findings suggest that the inhibition of PKM2 by compound 3K affected the Warburg effect and induced autophagic cell death. Therefore, use of specific PKM2 inhibitors to block the glycolytic pathway and target cancer cell metabolism represents a promising therapeutic approach for treating PKM2-overexpressing ovarian cancer.

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.

Natural products as a means of overcoming cisplatin chemoresistance in bladder cancer

Cisplatin remains an integral part of the treatment for muscle invasive bladder cancer. A large number of patients do not respond to cisplatin-based chemotherapy and efficacious salvage regimens are limited. Immunotherapy has offered a second line of treatment; however, only approximately 20% of patients respond, and molecular subtyping of tumors indicates there may be significant overlap in those patients that respond to cisplatin and those patients that respond to immunotherapy. As such, restoring sensitivity to cisplatin remains a major hurdle to improving patient care. One potential source of compounds for enhancing cisplatin is naturally derived bioactive products such as phytochemicals, flavonoids and others. These compounds can activate a diverse array of different pathways, many of which can directly promote or inhibit cisplatin sensitivity. The purpose of this review is to understand current drug development in the area of natural products and to assess how these compounds may enhance cisplatin treatment in bladder cancer patients.

Emerging small-molecule inhibitors of the Bruton's tyrosine kinase (BTK): Current development

Therapy based on Bruton's tyrosine kinase (BTK) inhibitors one of the major treatment options currently recommended for lymphoma patients. The first generation of BTK inhibitor, Ibrutinib, achieved remarkable progress in the treatment of B-cell malignancies, but still has problems with drug-resistance or off-target induced serious side effects. Therefore, numerous new BTK inhibitors were developed to address this unmet medical need. In parallel, the effect of BTK inhibitors against immune-related diseases has been evaluated in clinical trials. This review summarizes recent progress in the research and development of BTK inhibitors, with a focus on structural characteristics and structure-activity relationships. The structure-refinement process of representative pharmacophores as well as their effects on binding affinity, biological activity and pharmacokinetics profiles were analyzed. The advantages and disadvantages of reversible/irreversible BTK inhibitors and their potential implications were discussed to provide a reference for the rational design and development of novel potent BTK inhibitors.

The Role of PKM2 in Metabolic Reprogramming: Insights into the Regulatory Roles of Non-Coding RNAs

Pyruvate kinase is a key regulator in glycolysis through the conversion of phosphoenolpyruvate (PEP) into pyruvate. Pyruvate kinase exists in various isoforms that can exhibit diverse biological functions and outcomes. The pyruvate kinase isoenzyme type M2 (PKM2) controls cell progression and survival through the regulation of key signaling pathways. In cancer cells, the dimer form of PKM2 predominates and plays an integral role in cancer metabolism. This predominance of the inactive dimeric form promotes the accumulation of phosphometabolites, allowing cancer cells to engage in high levels of synthetic processing to enhance their proliferative capacity. PKM2 has been recognized for its role in regulating gene expression and transcription factors critical for health and disease. This role enables PKM2 to exert profound regulatory effects that promote cancer cell metabolism, proliferation, and migration. In addition to its role in cancer, PKM2 regulates aspects essential to cellular homeostasis in non-cancer tissues and, in some cases, promotes tissue-specific pathways in health and diseases. In pursuit of understanding the diverse tissue-specific roles of PKM2, investigations targeting tissues such as the kidney, liver, adipose, and pancreas have been conducted. Findings from these studies enhance our understanding of PKM2 functions in various diseases beyond cancer. Therefore, there is substantial interest in PKM2 modulation as a potential therapeutic target for the treatment of multiple conditions. Indeed, a vast plethora of research has focused on identifying therapeutic strategies for targeting PKM2. Recently, targeting PKM2 through its regulatory microRNAs, long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) has gathered increasing interest. Thus, the goal of this review is to highlight recent advancements in PKM2 research, with a focus on PKM2 regulatory microRNAs and lncRNAs and their subsequent physiological significance.

Simultaneous Inhibition of Ornithine Decarboxylase 1 and Pyruvate Kinase M2 Exerts Synergistic Effects Against Hepatocellular Carcinoma Cells

Purpose

Previously, we showed that lactate promoted the proliferation and mobility of hepatocellular carcinoma (HCC) cells by increasing the expression of ornithine decarboxylase 1 (ODC1). In this study, we determined the relationship between ODC1 and pyruvate kinase M2 (PKM2, a key lactate metabolism enzyme), and determined the combined effects of difluoromethylornithine (DFMO; an ODC1 inhibitor) and compound 3k (a PKM2 inhibitor) on HCC cells.

Methods

First, the relationship between PKM2 and ODC1 was analyzed using Western blotting, Cell Counting Kit (CCK)-8 assays, transwell assays, bioinformatics, quantitative real-time fluorescent PCR (qRT-PCR), and immunohistochemical staining. Thereafter, the ODC1 inhibitor DFMO and the PKM2 inhibitor compound 3k were employed. Their combined effects on HCC cell proliferation and mobility were evaluated via CCK-8 assay, flow cytometry, a subcutaneous xenograft tumor model in mice, wound healing assays, and transwell assays. Additionally, the effects of DFMO and compound 3k on the epithelial–mesenchymal transition phenotype and the AKT/GSK-3β/β-catenin pathway were explored using Western blotting and immunofluorescence.

Results

PKM2 knockdown significantly decreased the ODC1 expression, and the proliferation and invasion of HCC cells, while ODC1 overexpression reversed the inhibitory effects of PKM2 knockdown. Similarly, inhibition of ODC1 also decreased the expression of PKM2 via reducing the c-myc-induced transcription. PKM2 was co-expressed with ODC1 in HCC samples, while simultaneously upregulated PKM2 and ODC1 led to the poorest survival outcome. DFMO and compound 3k synergistically inhibited HCC cell proliferation, induced apoptosis, and suppressed cell mobility, as well as the EMT phenotype and the AKT/GSK-3β/β-catenin pathway. The AKT activator SC79 reversed the inhibitory effects.

Conclusion

PKM2/ODC1 are involved in a positive feedback loop. The simultaneous inhibition of ODC1 and PKM2 using DFMO and compound 3k exerts synergistic effects against HCC cells via the AKT/GSK-3β/β-catenin pathway. Thus, DFMO combined with compound 3k may be a novel effective strategy for treating HCC.