Activators of PKM2 in cancer metabolism

Novel sulfonamides unveiled as potent anti-lung cancer agents via tumor pyruvate kinase M2 activation

This rational pursuit led to the identification of a novel sulfonamide derivative as a potent anti-lung cancer (LC) compound. Considering these results, we synthesized 38 novel sulfonamide derivatives with diverse skeletal structures. In vitro cytotoxicity assays revealed a potent and selective antiproliferative effect against A549 cells after evaluating a panel of cancer cell lines. Compound 9b has emerged as a potent activator of tumor pyruvate kinase M2 (PKM2), a protein known to play a critical role in LC. Apoptosis assays and cell cycle analysis demonstrated early apoptosis and G2 phase arrest. In silico studies demonstrated interactions between compound 9b and the activator binding site of PKM2. Surface plasmon resonance (SPR) experiments strongly indicated that 9b has a high affinity (K d of 1.378 nM) for PKM2. Furthermore, the increase in reactive oxygen species and decrease in lactate concentration suggested that compound 9b has significant anticancer effects. Notably, the increase in particle size following treatment with 9b suggested the tetramerization of PKM2. This work provides insights that might advance efforts to develop effective non-platinum anticancer agents.

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

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

Beyond PD(L)-1 Blockade in Microsatellite-Instable Cancers: Current Landscape of Immune Co-Inhibitory Receptor Targeting

High microsatellite instability (MSI-H) derives from genomic hypermutability due to deficient mismatch repair function. Colorectal (CRC) and endometrial cancers (EC) are the tumor types that more often present MSI-H. Anti-PD(L)-1 antibodies have been demonstrated to be agnostically effective in patients with MSI-H cancer, but 50-60% of them do not respond to single-agent treatment, highlighting the necessity of expanding their treatment opportunities. Ipilimumab (anti-CTLA4) is the only immune checkpoint inhibitor (ICI) non-targeting PD(L)-1 that has been approved so far by the FDA for MSI-H cancer, namely, CRC in combination with nivolumab. Anti-TIM3 antibody LY3321367 showed interesting clinical activity in combination with anti-PDL-1 antibody in patients with MSI-H cancer not previously treated with anti-PD(L)-1. In contrast, no clinical evidence is available for anti-LAG3, anti-TIGIT, anti-BTLA, anti-ICOS and anti-IDO1 antibodies in MSI-H cancers, but clinical trials are ongoing. Other immunotherapeutic strategies under study for MSI-H cancers include vaccines, systemic immunomodulators, STING agonists, PKM2 activators, T-cell immunotherapy, LAIR-1 immunosuppression reversal, IL5 superagonists, oncolytic viruses and IL12 partial agonists. In conclusion, several combination therapies of ICIs and novel strategies are emerging and may revolutionize the treatment paradigm of MSI-H patients in the future. A huge effort will be necessary to find reliable immune biomarkers to personalize therapeutical decisions.

An insight into the structure-activity relationship studies of anticancer medicinal attributes of 7-azaindole derivatives: a review

In the current portfolio, there is a lot of interest in the 7-azaindole building block for drug discovery. The creation of synthetic, sophisticated methods for the modification of 7-azaindoles is a promising area of research. This review covers the structure-activity relationship of 7-azaindole analogs, which have been shown to be effective anticancer agents in the literature of the past two decades. Positions 1, 3 and 5 of the 7-azaindole ring are the most active sites. Disubstitution is used for the synthesis of a new analog of the 7-azaindole moiety. All positions are used to create novel molecules that are effective anticancer agents. The alkyl, aryl carboxamide group and heterocyclic ring are the most successful types of substitution.

Oridonin inhibits the occurrence and development of colorectal cancer by reversing the Warburg effect via reducing PKM2 dimer formation and preventing its entry into the nucleus

BACKGROUND

The Warburg effect is prevalent in human cancer. Oridonin (ORI) has excellent anticancer effects, but its exact anticancer mechanism is still unclear.

METHODS

CCK8, EdU, and flow cytometry assay were performed to detect the effect of ORI on cell viability, proliferation and apoptosis, respectively. RNA-seq was carried out to search the underlying mechanisms. Total PKM2, dimeric PKM2, nuclear PKM2 was detected by Western blot. The epidermal growth factor receptor/extracellular signal regulated kinase (EGFR/ERK) signaling was assayed. The binding ability of Importin-α5 to PKM2 was performed by Co-IP experiments. The effect of ORI combined with cysteine (Cys) or fructose-1, 6-diphosphate (FDP) on cancer cells was detected. Mouse xenograft model was established to confirm the molecular mechanisms in vivo.

RESULTS

ORI inhibited viability, proliferation and promoted apoptosis of CRC cells. RNA-seq revealed ORI attenuated the Warburg effect in cancer cells. ORI reduced dimeric PKM2 and prevented it from entering the nucleus. ORI did not affect the EGFR/ERK signaling, but reduced Importin-α5 binding to the PKM2 dimer. Cys or FDP reversed or enhanced the effect of ORI. Animal model assay confirmed the molecular mechanisms in vivo.

CONCLUSIONS

Our study first shows that ORI could have anticancer activity by inhibiting the Warburg effect as a novel activator of PKM2.

Knowledge-driven design and optimization of potent symmetric anticancer molecules: A case study on PKM2 activators

BACKGROUND

Pyruvate kinase M2 (PKM2) is preferentially expressed as a low-activity dimer over the active tetramer in proliferating tumor cells, resulting in metabolic reprogramming to achieve high energy requirements and nutrient uptake. This leads to a shift from the normal glycolytic pathway causing tumor cells to proliferate uncontrollably. This study utilizes knowledge-based drug discovery to determine the critical features from experimentally known PKM2 activators and design compounds that would significantly confer a stable structural and functional edge over the known compounds which are still at the preclinical stage.

METHODS

Conscientious molecular modeling studies were carried out and critical structural features were identified and validated from the knowledge of experimentally known PKM2 activators to confer high-binding affinities. A virtual library of 200 palindromic and non-palindromic activators was designed based on these identified critical features to target a distinct activator binding-site. This binding would favor specific dimer-dimer association and subsequent protein tetramerization. The resultant compounds strongly correlated with identified structural features and binding affinities which further strengthened our findings. The designed activators were then subjected to pharmacokinetic profiling and toxicity prediction, followed by free-binding energy calculations and MD simulations.

RESULTS

All the virtually designed activators comprising the identified critical features were observed to confer high-binding affinities ranging from -9.1 to -15.0 kcal/mol to the receptor protein. The designed activators also demonstrated optimum pharmacokinetic and toxicity profiles.

CONCLUSION

The best activators selected for MD simulations studies were conclusively observed to stabilize the required tetrameric conformation suggesting that these activators could potentially target PKM2 tetramerization that might restore the normal glycolytic pathway and suppress tumor progression.

LC/Q-TOF MS and LC/QQQ MS based bioanalysis of a new ferrocene derivative as a potential anticancer lead with promising drug-like characteristics

Pyrazolopyrimidine ring present in various approved drugs is reported to target the tyrosine kinase receptor. A new pyrazolopyrimidine ferrocene derivative, which targets tumor pyruvate kinase M2 showed an impressive antiproliferative profile against human oral squamous cell carcinoma cell line CAL27 assessed using Alamar blue assay. In line with the lead optimization process, the molecule was studied for physicochemical properties where a bioanalytical method has been developed in plasma on liquid chromatography-mass spectrometry and validated following the USFDA bioanalytical method validation guideline. Plasma stability and plasma protein binding potential of the molecule have been evaluated. All the major metabolites of the compound have been identified through in vitro metabolite study employing rat liver microsome, human liver microsome, and human S9 fractions. The in silico toxicity profile of the metabolites was assessed using ProTox II software. Log P, Log D, and pKa of the molecule were found to be 4.5, 5, and 12, respectively. The molecule was found to be quite stable in plasma and have a moderate affinity towards plasma proteins (about 75 % binding). Four major metabolites have been identified and characterized by UHPLCQ-TOF-MS. The metabolites were found to have a moderate safety profile. The validated bioanalytical method and the metabolic pathway will be useful for future clinical studies and to assess the safety profile of the molecule. The finding of this study may also be useful in analyzing the desired drug-like properties through bioanalysis while designing new chemical entities based on metallocenes.

Molecular glues: enhanced protein-protein interactions and cell proteome editing

The druggable genome is limited by structural features that can be targeted by small molecules in disease-relevant proteins. While orthosteric and allosteric protein modulators have been well studied, they are limited to antagonistic/agonistic functions. This approach to protein modulation leaves many disease-relevant proteins as undruggable targets. Recently, protein-protein interaction modulation has emerged as a promising therapeutic field for previously undruggable protein targets. Molecular glues and heterobifunctional degraders such as PROTACs can facilitate protein interactions and bring the proteasome into proximity to induce targeted protein degradation. In this review, we discuss the function and rational design of molecular glues, heterobifunctional degraders, and hydrophobic tag degraders. We also review historic and novel molecular glues and targets and discuss the challenges and opportunities in this new therapeutic field.

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.

A review on the emerging roles of pyruvate kinase M2 in anti-leukemia therapy

Glycolysis is an important step in respiration and provides energy for cellular processes. Pyruvate kinase M2 (PKM2), a key rate-limiting enzyme of glycolysis, plays an important role in tumor cell metabolism and proliferation. It is also specifically overexpressed in leukemia cells and contributes to leukemic proliferation, differentiation, and drug resistance through both aerobic glycolysis and non-metabolic pathways. In this review, the functions and regulatory roles of PKM2 are firstly introduced. Then, the molecular mechanisms of PKM2 in leukemogenesis are summarized. Next, reported PKM2 modulators and their anti-leukemia mechanisms are described. Finally, the current challenges and the potential opportunities of PKM2 inhibitors or agonists in leukemia therapy are discussed.

TEPP-46-Based AIE Fluorescent Probe for Detection and Bioimaging of PKM2 in Living Cells

Pyruvate kinase (PK) M2 (PKM2), a glycolytic enzyme, is a hallmark of different types of tumors and plays a significant role in the Warburg effect. However, there is no fluorescent probe for PKM2 that has been reported yet. In this study, TEPC466, a novel TEPP-46-based aggregation-induced emission (AIE) probe for the detection of PKM2, was designed, synthesized, and fully characterized by ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry. When the fluorescent agent, coumarine, was conjugated to TEPP-46, the bioprobe TEPC466 showed a high degree of selectivity and sensitivity for the detection of PKM2 protein via the AIE effect. TEPC466 was then successfully applied in imaging the PKM2 protein in colorectal cancer cells with low toxicity. Moreover, structure-based modeling and the PK activity assay confirmed that TEPC466 has a better binding with PKM2 than TEPP-46, which suggests that TEPC466 could also be a good agonist of PKM2. Taken together, the bioprobe shows potential in selective detection of PKM2 and provides a useful tool for cancer diagnosis and therapy.

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 of boronic acid-based potent activators of tumor pyruvate kinase M2 and development of gastroretentive nanoformulation for oral dosing

Several studies have established that cancer cells explicitly over-express the less active isoform of pyruvate kinase M2 (PKM2) is critical for tumorigenesis. The activation of PKM2 towards tetramer formation may increase affinity towards phosphoenolpyruvate (PEP) and avoidance of the Warburg effect. Herein, we describe the design, synthesis, and development of boronic acid-based molecules as activators of PKM2. The designed molecules were inspired by existing anticancer scaffolds and several fragments were assembled in the derivatives. 6a-6d were synthesized using a multi-step synthetic strategy in 55-70% yields, starting from cheap and readily available materials. The compounds were selectively cytotoxic to kill the cancerous cells at 80 nM, while they were non-toxic to the normal cells. The kinetic studies established the compounds as novel activators of PKM2 and (E/Z)-(4-(3-(2-((4-chlorophenyl)amino)-4-(dimethylamino)thiazol-5-yl)-2-(ethoxycarbonyl)-3-oxoprop-1-en-1-yl) phenyl)boronic acid (6c) emerged as the most potent derivative. 6c was further evaluated using various in silico tools to understand the molecular mechanism of tetramer formation. Docking studies revealed that 6c binds to the PKM2 dimer at the dimeric interface. Further to ascertain the binding site and mechanism of action, rigorous MD (molecular dynamics) simulations were undertaken, which led to the conclusion that 6c stabilizes the center of the dimeric interface that possibly promotes tetramer formation. We further planned to make a tablet of the developed molecule for oral delivery, but it was seriously impeded owing to poor aqueous solubility of 6c. To improve aqueous solubility and retain 6c at the lower gastrointestinal tract, thiolated chitosan-based nanoparticles (TCNPs) were prepared and further developed as tablet dosage form to retain anticancer potency in the excised goat colon. Our findings may provide a valuable pharmacological mechanism for understanding metabolic underpinnings that may aid in the clinical development of new anticancer agents targeting PKM2.

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.

Impact of diabetes on promoting the growth of breast cancer

BACKGROUND

Type II diabetes mellitus (DM2) is a significant risk factor for cancers, including breast cancer. However, a proper diabetic breast cancer mouse model is not well-established for treatment strategy design. Additionally, the precise diabetic signaling pathways that regulate cancer growth remain unresolved. In the present study, we established a suitable mouse model and demonstrated the pathogenic role of diabetes on breast cancer progression.

METHODS

We successfully generated a transgenic mouse model of human epidermal growth factor receptor 2 positive (Her2⁺ or ERBB2) breast cancer with DM2 by crossing leptin receptor mutant (Lepr^db/+ ) mice with MMTV-ErbB2/neu) mice. The mouse models were administrated with antidiabetic drugs to assess the impacts of controlling DM2 in affecting tumor growth. Magnetic resonance spectroscopic imaging was employed to analyze the tumor metabolism.

RESULTS

Treatment with metformin/rosiglitazone in MMTV-ErbB2/Lepr^db/db mouse model reduced serum insulin levels, prolonged overall survival, decreased cumulative tumor incidence, and inhibited tumor progression. Anti-insulin resistance medications also inhibited glycolytic metabolism in tumors in vivo as indicated by the reduced metabolic flux of hyperpolarized ¹³ C pyruvate-to-lactate reaction. The tumor cells from MMTV-ErbB2/Lepr^db/db transgenic mice treated with metformin had reprogrammed metabolism by reducing levels of both oxygen consumption and lactate production. Metformin decreased the expression of Myc and pyruvate kinase isozyme 2 (PKM2), leading to metabolism reprogramming. Moreover, metformin attenuated the mTOR/AKT signaling pathway and altered adipokine profiles.

CONCLUSIONS

MMTV-ErbB2/Lepr^db/db mouse model was able to recapitulate diabetic HER2⁺ human breast cancer. Additionally, our results defined the signaling pathways deregulated in HER2⁺ breast cancer under diabetic condition, which can be intervened by anti-insulin resistance therapy.

Pharmacological activation of pyruvate kinase M2 reprograms glycolysis leading to TXNIP depletion and AMPK activation in breast cancer cells

Background

Aerobic glycolysis, discovered by Otto Warburg, is a hallmark of cancer metabolism even though not yet fully understood. The low activity of the cancerous pyruvate kinase isozyme (M2) is thought to play an important role by facilitating the conversion of glycolytic intermediates to other anabolic pathways to support tumors’ high proliferation rate.

Methods

Five breast cancer cell lines representing different molecular subtypes were used in this study where real time measurements of cellular bioenergetics and immunoblotting analysis of energy- and nutrient-sensing pathways were employed to investigate the potential effects of PKM2 allosteric activator (DASA-58) in glucose rewiring.

Results

In this study, we show that DASA-58 can induce pyruvate kinase activity in breast cancer cells without affecting the overall cell survival. The drug is also able to reduce TXNIP levels (an intracellular glucose sensor) probably through depletion of upstream glycolytic metabolites and independent of AMPK and ER signaling. AMPK shows an induction in phosphorylation (T172) in response to treatment an effect that can be potentiated by combining DASA-58 with other metabolic inhibitors.

Conclusions

Altogether, the multifaceted metabolic reprogramming induced by DASA-58 in breast cancer cells increases their susceptibility to other therapeutics suggesting the suitability of the intracellular glucose sensor TXNIP as a marker of PK activity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40170-021-00239-8.

Protein kinase function of pyruvate kinase M2 and cancer

Pyruvate kinase is a terminal enzyme in the glycolytic pathway, where it catalyzes the conversion of phosphoenolpyruvate to pyruvate and production of ATP via substrate level phosphorylation. PKM2 is one of four isoforms of pyruvate kinase and is widely expressed in many types of tumors and associated with tumorigenesis. In addition to pyruvate kinase activity involving the metabolic pathway, increasing evidence demonstrates that PKM2 exerts a non-metabolic function in cancers. PKM2 has been shown to be translocated into nucleus, where it serves as a protein kinase to phosphorylate various protein targets and contribute to multiple physiopathological processes. We discuss the nuclear localization of PKM2, its protein kinase function and association with cancers, and regulation of PKM2 activity.

Primary prostate cancer educates bone stroma through exosomal pyruvate kinase M2 to promote bone metastasis

Prostate cancer (PCa) metastasizes selectively to bone through unknown mechanisms. In the current study, we identified exosome-mediated transfer of pyruvate kinase M2 (PKM2) from PCa cells into bone marrow stromal cells (BMSCs) as a novel mechanism through which primary tumor-derived exosomes promote premetastatic niche formation. We found that PKM2 up-regulates BMSC CXCL12 production in a HIF-1α-dependent fashion, which subsequently enhances PCa seeding and growth in the bone marrow. Furthermore, serum-derived exosomes from patients with either primary PCa or PCa metastasis, as opposed to healthy men, reveal that increased exosome PKM2 expression is associated with metastasis, suggesting clinical relevance of exosome PKM2 in PCa. Targeting the exosome-induced CXCL12 axis diminished exosome-mediated bone metastasis. In summary, primary PCa cells educate the bone marrow to create a premetastatic niche through primary PCa exosome-mediated transfer of PKM2 into BMSCs and subsequent up-regulation of CXCL12. This novel mechanism indicates the potential for exosome PKM2 as a biomarker and suggests therapeutic targets for PCa bone metastasis.

Pyruvate Kinase M2: a Metabolic Bug in Re-Wiring the Tumor Microenvironment

Metabolic reprogramming is a newly emerged hallmark of cancer attaining a recent consideration as an essential factor for the progression and endurance of cancer cells. A prime event of this altered metabolism is increased glucose uptake and discharge of lactate into the cells surrounding constructing a favorable tumor niche. Several oncogenic factors help in promoting this consequence including, pyruvate kinase M2 (PKM2) a rate-limiting enzyme of glycolysis in tumor metabolism via exhibiting its low pyruvate kinase activity and nuclear moon-lightening functions to increase the synthesis of lactate and macromolecules for tumor proliferation. Not only its role in cancer cells but also its role in the tumor microenvironment cells has to be understood for developing the small molecules against it which is lacking with the literature till date. Therefore, in this present review, the role of PKM2 with respect to various tumor niche cells will be clarified. Further, it highlights the updated list of therapeutics targeting PKM2 pre-clinically and clinically with their added limitations. This upgraded understanding of PKM2 may provide a pace for the reader in developing chemotherapeutic strategies for better clinical survival with limited resistance.

Dimethylaminomicheliolide (DMAMCL) Suppresses the Proliferation of Glioblastoma Cells via Targeting Pyruvate Kinase 2 (PKM2) and Rewiring Aerobic Glycolysis

Glioblastoma (GBM) is the most prevalent malignant tumor in the central nervous system. Aerobic glycolysis, featured with elevated glucose consumption and lactate production, confers selective advantages on GBM by utilizing nutrients to support rapid cell proliferation and tumor growth. Pyruvate kinase 2 (PKM2), the last rate-limiting enzyme of glycolysis, is known to regulate aerobic glycolysis, and considered as a novel cancer therapeutic target. Herein, we aim to describe the cellular functions and mechanisms of a small molecular compound dimethylaminomicheliolide (DMAMCL), which has been used in clinical trials for recurrent GBM in Australia. Our results demonstrate that DMAMCL is effective on the inhibition of GBM cell proliferation and colony formation. MCL, the active metabolic form of DMAMCL, selectively binding to monomeric PKM2 and promoting its tetramerization, was also found to improve the pyruvate kinase activity of PKM2 in GBM cells. In addition, non-targeting metabolomics analysis reveals multiple metabolites involved in glycolysis, including lactate and glucose-6-phosphate, are decreased with DMAMCL treatment. The inhibitory effects of DMAMCL are observed to decrease in GBM cells upon PKM2 depletion, further confirming the importance of PKM2 in DMAMCL sensitivity. In conclusion, the activation of PKM2 by DMAMCL results in the rewiring aerobic glycolysis, which consequently suppresses the proliferation of GBM cells. Hence, DMAMCL represents a potential PKM2-targeted therapeutic agent against GBM.

Prognostic Value of Lactate Dehydrogenase Expression in Different Cancers: A Meta-Analysis

BACKGROUND

This meta-analysis was performed to elucidate the association between the expression of lactate dehydrogenase (LDH) and the prognosis of various malignant neoplasms.

MATERIALS AND METHODS

Qualified studies were systematically identified from relevant databases, including PubMed, Cochrane Library, Embase, WanFang, and HowNet. A total of 17 eligible studies with 4,176 patients that complied with the inclusion criteria were enrolled in this meta-analysis. The 17 articles were published from 2011 to 2018. The hazard ratio (HR) and 95% confidence interval (95%CI) were obtained from the selected studies.

RESULTS

The analysis that included all LDH-related studies showed a significant association with the overall survival (OS) outcome (HR = 1.74, P = 0.001) but exhibited an insignificant association with the disease-free survival (DFS) or recurrence-free survival (RFS) outcome (HR = 1.40, P = 0.072). High lactate dehydrogenase A (LDHA) expression was significantly relevant to inferior OS (HR = 1.88, 95%CI: 1.37-2.59) and DFS or RFS (HR = 1.56, 95%CI: 1.29-1.89).

CONCLUSIONS

High LDH expression and the prognostic outcome of various cancer patients are significantly correlated. High LDHA expression is a promising biomarker for forecasting the survival of patients and the recurrence of different cancers in these patients. Further associative studies are required due to the complex role of LDH genes.

Inhibition of hepatocellular carcinoma by metabolic normalization

In two different mouse liver cancer models, we recently showed that a switch from oxidative phosphorylation (Oxphos) to glycolysis (the Warburg effect) is invariably accompanied by a marked decline in fatty acid oxidation (FAO) and a reciprocal increase in the activity of pyruvate dehydrogenase (PDH), which links glycolysis to the TCA cycle. We now show that short-term implementation of either medium-chain (MC) or long-chain (LC) high fat diets (HFDs) nearly doubled the survival of mice with c-Myc oncoprotein-driven hepatocellular carcinoma (HCC). Mechanistically, HFDs forced tumors to become more reliant on fatty acids as an energy source, thus normalizing both FAO and PDH activities. More generally, both MC- and LC-HFDs partially or completely normalized the expression of 682 tumor-dysregulated transcripts, a substantial fraction of which are involved in cell cycle control, proliferation and metabolism. That these same transcripts were responsive to HFDs in livers strongly suggested that the changes were the cause of tumor inhibition rather than its consequence. In seven different human cancer cohorts, patients with tumors containing high ratios of FAO-related:glycolysis-related transcripts had prolonged survival relative to those with low ratios. Furthermore, in 13 human cancer types, the expression patterns of transcripts encoding enzymes participating in FAO and/or cholesterol biosynthesis also correlated with significantly prolonged survival. Collectively, our results support the idea that the survival benefits of HFDs are due to a reversal of the Warburg effect and other tumor-associated metabolic and cell cycle abnormalities. They also suggest that short-term dietary manipulation, either alone or in combination with more traditional chemotherapeutic regimens, might be employed as a relatively non-toxic and cost-effective means of enhancing survival in certain cancer types.

Synthesis of novel 7-azaindole derivatives containing pyridin-3-ylmethyl dithiocarbamate moiety as potent PKM2 activators and PKM2 nucleus translocation inhibitors

Multiple lines of evidence have indicated that pyruvate kinase M2 (PKM2) is upregulated in most cancer cells and it is increasingly recognized as a potential therapeutic target in oncology. In a continuation of our discovery of lead compound 5 and SAR study, the 7-azaindole moiety in compound 5 was systematically optimized. The results showed that compound 6f, which has a difluoroethyl substitution on the 7-azaindole ring, exhibited high PKM2 activation potency and anti-proliferation activities on A375 cell lines. In a xenograft mouse model, oral administration of compound 6f led to significant tumor regression without obvious toxicity. Further mechanistic studies revealed that 6f could influence the translocation of PKM2 into nucleus, as well as induction of apoptosis and autophagy of A375 cells. More importantly, compound 6f significantly inhibited migration of A375 cells in a concentration-dependent manner. Collectively, 6f may serve as a lead compound in the development of potent PKM2 activators for cancer therapy.

Role of PKM2 in directing the metabolic fate of glucose in cancer: a potential therapeutic target

BACKGROUND

Many of the hallmarks of cancer are not inherently unique to cancer, but rather represent a re-enactment of normal host responses and activities. A vivid example is aerobic glycolysis ('Warburg effect'), which is used not only by cancer cells but also by normal cells that undergo rapid proliferation. A common feature of this metabolic adaptation is a shift in the expression of pyruvate kinase (PK) isoform M1 to isoform M2. Here, we highlight the key role of PKM2 in shifting cancer metabolism between ATP production and biosynthetic processes. Since anabolic processes are highly energy dependent, the fate of glucose in energy production versus the contribution of carbon in biosynthetic processes needs to be finely synchronised. PKM2 acts to integrate cellular signalling and allosteric regulation of metabolites in order to align metabolic activities with the changing needs of the cell.

CONCLUSIONS

The central role of PKM2 in directing the flow of carbon between catabolic (ATP-producing) and anabolic processes provides unique opportunities for extending the therapeutic window of currently available and/or novel anti-neoplastic agents.

An allostatic mechanism for M2 pyruvate kinase as an amino-acid sensor

We have tested the effect of all 20 proteinogenic amino acids on the activity of the M2 isoenzyme of pyruvate kinase (M2PYK) and show that, within physiologically relevant concentrations, phenylalanine, alanine, tryptophan, methionine, valine, and proline act as inhibitors, while histidine and serine act as activators. Size exclusion chromatography has been used to show that all amino acids, whether activators or inhibitors, stabilise the tetrameric form of M2PYK. In the absence of amino-acid ligands an apparent tetramer–monomer dissociation K_d is estimated to be ∼0.9 µM with a slow dissociation rate (t_1/2∼15 min). X-ray structures of M2PYK complexes with alanine, phenylalanine, and tryptophan show the M2PYK locked in an inactive T-state conformation, while activators lock the M2PYK tetramer in the active R-state conformation. Amino-acid binding in the allosteric pocket triggers rigid body rotations (11°) stabilising either T or R states. The opposing inhibitory and activating effects of the non-essential amino acids serine and alanine suggest that M2PYK could act as a rapid-response nutrient sensor to rebalance cellular metabolism. This competition at a single allosteric site between activators and inhibitors provides a novel regulatory mechanism by which M2PYK activity is finely tuned by the relative (but not absolute) concentrations of activator and inhibitor amino acids. Such ‘allostatic’ regulation may be important in metabolic reprogramming and influencing cell fate.

AKT2 contributes to increase ovarian cancer cell migration and invasion through the AKT2-PKM2-STAT3/NF-κB axis

Multiple studies have shown that protein kinase Bβ (AKT2) is involved in the development and progression of ovarian cancer, however, its precise role remains unclear. Here we explored the underlying molecular mechanisms how AKT2 promotes ovarian cancer progression. We examined the effects of AKT2 in vitro in two ovarian cancer cell lines (SKOV3 and HEY), and in vivo by metastasis assay in nude mice. The migration and invasion ability of SKOV3 and HEY cells was determined by transwell assay. Overexpression and knockdown (with shRNA) experiments were carried out to unravel the underlying signaling mechanisms induced by AKT2. Overexpression of AKT2 led to increased expression of pyruvate kinase (PKM2) in ovarian cancer cells and in lung metastatic foci from nude mice. Elevated AKT2/PKM2 expression induced cell migration and invasion in vitro, as well as lung metastasis in vivo; silencing AKT2 blocked these effects. Meanwhile, PKM2 overexpression was unable to increase AKT2 expression. The expressions of p-PI3K, p-AKT2, and PKM2 were increased when stimulated by epidermal growth factor (EGF); however, these expressions were blocked when inhibited the PI3K by LY294002. STAT3 expression was elevated and NF-κB p65 nuclear translocation was activated both in vitro and in vivo when either AKT2 or PKM2 was overexpressed; and these effects were inhibited when silencing AKT2 expression. Taken together, AKT2 increases the migration and invasion of ovarian cancer cells in vitro and promotes lung metastasis in nude mice in vivo through PKM2-mediated elevation of STAT3 expression and NF-κB activation. In conclusion, we highlight a novel mechanism of the AKT2-PKM2-STAT3/NF-κB axis in the regulation of ovarian cancer progression, and our work suggested that both AKT2 and PKM2 may be potential targets for the treatment of ovarian cancer.

Specific tumor-derived CCL2 mediated by pyruvate kinase M2 in colorectal cancer cells contributes to macrophage recruitment in tumor microenvironment

Development of colorectal cancer has been considered as a result of imbalance of pro- and anti-inflammatory intestinal microenvironment accompanied by macrophage recruitment. Despite macrophages are implicated in remodeling tumor microenvironment, the mechanism of macrophage recruitment is not fully elucidated yet. In this study, we reported clinical association of highly expressed pyruvate kinase M2 in colorectal cancer with macrophage attraction. The conditioned medium from Caco-2 and HT-29 cells with depleted pyruvate kinase M2 dramatically reduced macrophage recruitment, which is reversed by addition of, a critical chemotaxis factor to macrophage migration, rCCL2. Silencing of endogenous pyruvate kinase M2 markedly decreased CCL2 expression and secretion by real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. Endogenous pyruvate kinase M2 interacted with p65 and mediated nuclear factor-κB signaling pathway and mainly regulated phosphorylation of Ser276 on p65 nuclear factor-κB. In addition, inhibition of macrophage recruitment caused by pyruvate kinase M2 silencing was rescued by ectopic expression of p65. Interestingly, pyruvate kinase M2 highly expressed in colorectal cancer tissue, which is correction with macrophage distribution. Taken together, we revealed a novel mechanism of pyruvate kinase M2 in promoting colorectal cancer progression by recruitment of macrophages through p65 nuclear factor-κB-mediated expression of CCL2.

Induction of apoptosis by FFJ-5, a novel naphthoquinone compound, occurs via downregulation of PKM2 in A549 and HepG2 cells

Pyruvate kinase isoenzyme M2 (PKM2) has previously been identified as a tumor biomarker and as a potential target for cancer therapy. In this study, F§FJ-5, a characterized naphthoquinone modifier of mollugin, was synthesized in order to investigate its anticancer activity and the potential mechanisms. It was observed that FFJ-5 inhibited the cell growth of human lung adenocarcinoma cells A549 and human hepatoma cells HepG2 by MTT assays. FFJ-5 arrested cell cycle at the G2/M phase. Further analyses demonstrated that FFJ-5 attenuated the expression of PKM2 and reduced the production of adenosine triphosphate (ATP). Reduced expression and activity of epidermal growth factor receptor (EGFR) and Akt were observed in A549 and HepG2 cells exposed to FFJ-5. FFJ-5 exposure also resulted in cell apoptosis, in association with decreased intracellular pH level and mitochondrial membrane potential. In addition, FFJ-5 activated the caspase-3 cascade. In conclusion, FFJ-5 inhibited cancer cell growth via the blocking the EGFR-Akt-PKM2 pathway or through the synergistic action of EGFR, Akt and PKM2 proteins, alongside a decrease in ATP production. In addition, FFJ-5 induced cancer cell apoptosis by decreasing the intracellular pH level and the mitochondrial apoptosis pathway. The present results suggest a potential role of FFJ-5 on the therapy of human cancer.

Concordance between somatic copy number loss and down-regulated expression: A pan-cancer study of cancer predisposition genes

Cancer predisposition genes (CPGs) are a class of cancer genes in which germline variants lead to increased risk of cancer. Research has revealed that copy number variation (CNV) may be linked to cancer susceptibility in CPGs. In this pan-cancer analysis, we explored the relationship between somatic CNV and gene expression changes in CPGs. Based on curated 827 human CPGs from literature, we firstly identified 729 CPGs with precise CNV information from 5067 tumor samples using TCGA CNV data. Among them, 128 CPGs tended to have more frequent copy number losses (CNLs) compared with copy number gains (CNGs). Then by correlating these CNV data with TCGA gene expression data, we obtained 49 CPGs with concordant CNLs and gene down-regulation. Intriguingly, five CPGs showed concordance between CNL and down-regulation in 50 or more tumor samples: MTAP (216 samples), PTEN (143), MCPH1 (86), SMAD4 (63), and MINPP1 (51), which may represent the recurrent driving force for gene expression change during oncogenesis. Moreover, network analysis revealed that these 49 CPGs were tightly connected. In summary, this study provides the first observation of concordance between CNLs and down-regulation of CPGs in pan-cancer, which may help better understand the CPG biology in tumorigenesis and cancer progression.

Up-regulation of PKM2 promote malignancy and related to adverse prognostic risk factor in human gallbladder cancer

Recently, pyruvate kinase M2 (PKM2) has been implicated in the progression of certain cancers and might play pivotal roles in the formation of malignancy. However, the role of PKM2 in gallbladder cancer had not been well investigated. This study analyzed associations between PKM2 expression status with various clinical and pathologic parameters in a large cohort of gallbladder cancer (GBC) patients from a long term follow up results. The expression level of pyruvate kinase isotypes in GBC tissues and their adjacent normal gallbladder tissues were estimated by qRT-PCR and Western blot. PKM2 mRNA level were significantly high in gallbladder cancer tissues than in adjacent noncancerous tissues (P < 0.001). High expression of the PKM2 was detected in 55.71% paraffin-embedded GBC tissue. The high PKM2 expression was independently associated with poorer overall survival in patients with GBC (median survival 11.9 vs 30.1 months; hazard ratio 2.79; 95% CI = 1.18 to 6.55; P = 0.02). These findings indicated elevated expression of PKM2 is a prognostic factor for poor GBC clinical outcomes, implied involving of PKM2 in GBC progression.

Pyruvate Kinase M2 and Lactate Dehydrogenase A Are Overexpressed in Pancreatic Cancer and Correlate with Poor Outcome

Pancreatic cancer has a 5-year survival rate of less than 4%. Despite advances in diagnostic technology, pancreatic cancer continues to be diagnosed at a late and incurable stage. Accurate biomarkers for early diagnosis and to predict treatment response are urgently needed. Since alteration of glucose metabolism is one of the hallmarks of cancer cells, we proposed that pyruvate kinase type M2 (M2PK) and lactate dehydrogenase A (LDHA) enzymes could represent novel diagnostic markers and potential therapeutic targets in pancreatic cancer. In 266 tissue sections from normal pancreas, pancreatic cystic neoplasms, pancreatic intraepithelial neoplasia (PanIN) and cancer, we evaluated the expression of PKM2, LDHA, Ki-67 and CD8+ by immunohistochemistry and correlated these markers with clinicopathological characteristics and patient survival. PKM2 and LDHA expression was also assessed by Western blot in 10 human pancreatic cancer cell lines. PKM2 expression increased progressively from cyst through PanIN to cancer, whereas LDHA was overexpressed throughout the carcinogenic process. All but one cell line showed high expression of both proteins. Patients with strong PKM2 and LDHA expression had significantly worse survival than those with weak PKM2 and/or LDHA expression (7.0 months vs. 27.9 months, respectively, p = 0.003, log rank test). The expression of both PKM2 and LDHA correlated directly with Ki-67 expression, and inversely with intratumoral CD8+ cell count. PKM2 was significantly overexpressed in poorly differentiated tumours and both PKM2 and LDHA were overexpressed in larger tumours. Multivariable analysis showed that combined expression of PKM2 and LDHA was an independent poor prognostic marker for survival. In conclusion, our results demonstrate a high expression pattern of two major glycolytic enzymes during pancreatic carcinogenesis, with increased expression in aggressive tumours and a significant adverse effect on survival.

MYCN controls an alternative RNA splicing program in high-risk metastatic neuroblastoma

The molecular mechanisms underlying the aggressive behavior of MYCN driven neuroblastoma (NBL) is under intense investigation; however, little is known about the impact of this family of transcription factors on the splicing program. Here we used high-throughput RNA sequencing to systematically study the expression of RNA isoforms in stage 4 MYCN-amplified NBL, an aggressive subtype of metastatic NBL. We show that MYCN-amplified NBL tumors display a distinct gene splicing pattern affecting multiple cancer hallmark functions. Six splicing factors displayed unique differential expression patterns in MYCN-amplified tumors and cell lines, and the binding motifs for some of these splicing factors are significantly enriched in differentially-spliced genes. Direct binding of MYCN to promoter regions of the splicing factors PTBP1 and HNRNPA1 detected by ChIP-seq demonstrates that MYCN controls the splicing pattern by direct regulation of the expression of these key splicing factors. Furthermore, high expression of PTBP1 and HNRNPA1 was significantly associated with poor overall survival of stage4 NBL patients (p ≤ 0.05). Knocking down PTBP1, HNRNPA1 and their downstream target PKM2, an isoform of pro-tumor-growth, result in repressed growth of NBL cells. Therefore, our study reveals a novel role of MYCN in controlling global splicing program through regulation of splicing factors in addition to its well-known role in the transcription program. These findings suggest a therapeutically potential to target the key splicing factors or gene isoforms in high-risk NBL with MYCN-amplification.

PKM2 and cancer: The function of PKM2 beyond glycolysis

Metabolic reprogramming is a hallmark of cancer cells and is used by cancer cells for growth and survival. Pyruvate kinase muscle isozyme M2 (PKM2) is a limiting glycolytic enzyme that catalyzes the final step in glycolysis, which is key in tumor metabolism and growth. The present review discusses the expression and regulation of PKM2, and reports the dominant role that PKM2 plays in glycolysis to achieve the nutrient demands of cancer cell proliferation. In addition, the present study discusses the non-metabolic function of PKM2, and its role as a coactivator and protein kinase, which contributes to tumorigenesis. Furthermore, conflicting studies concerning the role of PKM2 as a therapeutic target are reviewed. The improved understanding of PKM2 may provide a noval approach for cancer treatment.

High Expression of Pyruvate Kinase M2 is Associated with Chemosensitivity to Epirubicin and 5-Fluorouracil in Breast Cancer

BACKGROUND

Pyruvate kinase M2 (PKM2) is the key enzyme in the Warburg effect, and it was recently reported to be involved in the metabolic pathways of chemotherapeutic drugs. However, the role of PKM2 in breast cancer and its influence in the sensitivity to front-line anticancer drugs remains unclear.

METHODS

In this study, we examined the correlation between the expression of PKM2 and the sensitivity of primary breast cancer cells to anticancer drugs. PKM2 expression was studied by immunohistochemistry using biopsy samples of 296 patients diagnosed with invasive breast carcinoma, and the collagen gel droplet embedded culture-drug sensitivity tests (CD-DST) was conducted to all the patients to detect in vitro chemosensitivity after surgery.

RESULTS

We found high PKM2 expression was significantly associated with in vitro chemosensitivity to epirubicin (EPI) (P=0.019) and 5-fluorouracil (5-Fu) (P=0.009) in breast cancer patients. Then we used a small group of neoadjuvant chemotherapy cases to confirm that the higher PKM2 expression, the better pathological response to therapy was obtained in patients treated with EPI-based or EPI plus 5-Fu chemotherapy regimens. Although univariate and multivariate analysis indicated that high PKM2 was a poor independent predictor of progression free survival (PFS) and overall survival (OS) in breast cancer, patients with PKM2 high expression who received EPI-based or EPI plus 5-Fu chemotherapy were found to have a longer PFS (P=0.003, P=0.013) and OS (P=0.003, P=0.004) than patients treated with non-EPI/5-Fu-based regimens, respectively.

CONCLUSIONS

Our findings confirmed the poor prognosis of high PKM2 expression in breast cancer patients and revealed the predictive value of high PKM2 in the therapeutic response to EPI and 5-Fu. Moreover, our results provide the guidance of individual treatment for breast cancer patients who are foreboded a poor prognosis by the presence of high PKM2 status.