LY294002 inhibits the Warburg effect in gastric cancer cells by downregulating pyruvate kinase M2

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.

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.

Dual Hyaluronic Acid and Folic Acid Targeting pH-Sensitive Multifunctional 2DG@DCA@MgO-Nano-Core-Shell-Radiosensitizer for Breast Cancer Therapy

Simple Summary

In this study, we have developed CD44 and folate receptor-targeting multi-functional dual drug-loaded nanoparticles. This comprises hyaluronic acid (HA) and folic acid (FA) conjugated to 2-deoxy glucose (2DG) and a shell linked to a dichloroacetate (DCA) and magnesium oxide (MgO) core (2DG@DCA@MgO; DDM) to enhance the localized chemo-radiotherapy for effective breast cancer (BC) treatment. The physicochemical properties of nanoparticles including stability, selectivity, responsive release to pH, cellular uptake, and anticancer efficacy were comprehensively examined. Mechanistically, we identified multiple component signal pathways as important regulators of BC metabolism and mediators for the inhibitory effects exerted by DDM. Nanoparticles exhibited sustained DDM release properties in bio-relevant media, which was responsive to acidic pH providing edibility to the control of drug release from nanoparticles. DDM-loaded and HA–FA-functionalized nanoparticles exhibited increased selectivity and uptake by BC cells. Cell-based assays indicated that the functionalized DDM significantly suppressed cancer cell growth and boosted radiotherapy (RT) efficacy via inducing cell cycle arrest, enhancing apoptosis, and modulating glycolytic and OXPHOS pathways. Accordingly, the inhibition of glycolysis/OXPHOS by DDM and RT treatment may result in cancer metabolic reprogramming via a novel PI3K/AKT/mTOR/P53NF-κB/VEGF pathway in BC cells. Therefore, the dual targeting of glycolysis/OXPHOS pathways is suggested as a promising antitumor strategy.

Abstract

Globally, breast cancer (BC) poses a serious public health risk. The disease exhibits a complex heterogeneous etiology and is associated with a glycolytic and oxidative phosphorylation (OXPHOS) metabolic reprogramming phenotype, which fuels proliferation and progression. Due to the late manifestation of symptoms, rigorous treatment regimens are required following diagnosis. Existing treatments are limited by a lack of specificity, systemic toxicity, temporary remission, and radio-resistance in BC. In this study, we have developed CD44 and folate receptor-targeting multi-functional dual drug-loaded nanoparticles. This composed of hyaluronic acid (HA) and folic acid (FA) conjugated to a 2-deoxy glucose (2DG) shell linked to a layer of dichloroacetate (DCA) and a magnesium oxide (MgO) core (2DG@DCA@MgO; DDM) to enhance the localized chemo-radiotherapy for effective BC treatment. The physicochemical properties of nanoparticles including stability, selectivity, responsive release to pH, cellular uptake, and anticancer efficacy were thoroughly examined. Mechanistically, we identified multiple component signaling pathways as important regulators of BC metabolism and mediators for the inhibitory effects elicited by DDM. Nanoparticles exhibited sustained DDM release properties in a bio-relevant media, which was responsive to the acidic pH enabling eligibility to the control of drug release from nanoparticles. DDM-loaded and HA–FA-functionalized nanoparticles exhibited increased selectivity and uptake by BC cells. Cell-based assays revealed that the functionalized DDM significantly suppressed cancer cell growth and improved radiotherapy (RT) through inducing cell cycle arrest, enhancing apoptosis, and modulating glycolytic and OXPHOS pathways. By highlighting DDM mechanisms as an antitumor and radio-sensitizing reagent, our data suggest that glycolytic and OXPHOS pathway modulation occurs via the PI3K/AKT/mTOR/NF-κB/VEGF_low and P53_high signaling pathway. In conclusion, the multi-functionalized DDM opposed tumor-associated metabolic reprogramming via multiple signaling pathways in BC cells as a promising targeted metabolic approach.

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.

Expression and clinical significance of pyruvate kinase M2 in breast cancer: A protocol for meta-analysis and bioinformatics validation analysis

BACKGROUND

Breast cancer is a common malignant tumor in women. In recent years, its incidence is increasing year by year, and its morbidity and mortality rank the first place among female malignant tumors. Some key enzymes and intermediates in glycolysis are closely related to tumor development. Pyruvate kinase M2 (PKM2) is an important rate-limiting enzyme in glycolysis pathway. Meanwhile, it is highly expressed in proliferative cells, especially in tumor cells, and plays an important role in the formation of Warburg effect and tumorigenesis. Previous studies have explored the effects of PKM2 expression on the prognosis and clinical significance of breast cancer patients, while the results are contradictory and uncertain. This study uses controversial data for meta-analysis to accurately evaluate the problem. We collected relevant Oncomine and The Cancer Genome Atlas (TCGA) data to further verify the results. Through bioinformatics analysis, the mechanism and related pathways of PKM2 in breast cancer are explored.

METHODS

We searched Wanfang, Chinese Biomedical Literature Database, Chinese National Knowledge Infrastructure, the Chongqing VIP Chinese Science and Technology Periodical Database, PubMed, Embase, and Web of Science databases from inception to March 2021. The language restrictions are Chinese and English. The published literatures on PKM2 expression and prognosis or clinicopathological characteristics of breast cancer patients were statistically analyzed. Combined hazard ratios (HRs), odds ratios (ORs), and 95% confidence intervals (95% CIs) were used to evaluate the effects of PKM2 on the prognosis and clinicopathological features of breast cancer. Stata 14.0 software was applied for meta-analysis. Oncomine and TCGA databases were used to meta-analyze the differences of PKM2 mRNA expression between breast cancer and normal breast tissues. The expression of PKM2 protein was verified by Human Protein Atlas (HPA) database. The relationship between the gene and the survival of breast cancer patients was analyzed by Gene Expression Profiling Interactive Analysis (GEPIA). The relationship between PKM2 gene and clinicopathological characteristics was analyzed by using LinkedOmics, and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment pathway analysis was performed by using Metascape. Protein-protein interaction (PPI) network was constructed by String website.

RESULTS

The results of this meta-analysis will be submitted to a peer-reviewed journal for publication.

CONCLUSION

This study provides high-quality medical evidence for the correlation between the expression of PKM2 and the prognosis and clinicopathological features of breast cancer. Through bioinformatics analysis, this study further deepens the understanding of the mechanism and related pathways of PKM2 in breast cancer.

ETHICS AND DISSEMINATION

The private information from individuals will not be published. This systematic review also should not damage participants' rights. Ethical approval is not available. The results may be published in a peer-reviewed journal or disseminated in relevant conferences.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/W52HB.

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.

Gastric Cancer Heterogeneity and Clinical Outcomes

Gastric adenocarcinoma is a highly aggressive disease with poor overall survival. The aggressive nature of this disease is in part due to the high intra and inter tumoral heterogeneity and also due to the late diagnosis at presentation. Once progression occurs, treatment is more difficult due to the adaptation of tumors, which acquires resistance to commonly used chemotherapeutics. In this report, using publicly available data sets and pathway analysis, we highlight the vast heterogeneity of gastric cancer by investigating genes found to be significantly perturbed. We found several upregulated genes in the diffuse gastric cancer subtypes share similarity to gastric cancer as a whole which can be explained by the increase in this subtype of gastric cancer throughout the world. We report significant downregulation of genes that are underrepresented within the literature, such as ADH7, GCNT2, and LIF1, while other genes have not been explored within gastric cancer to the best of our knowledge such as METTL7A, MAL, CWD43, and SLC2A12. We identified gender to be another heterogeneous component of this disease and suggested targeted treatment strategies specific to this heterogeneity. In this study, we provide an in-depth exploration of the molecular landscape of gastric cancer in order to shed light onto novel areas of gastric cancer research and explore potential new therapeutic targets.

Long non‑coding RNA BCYRN1 promotes glycolysis and tumor progression by regulating the miR‑149/PKM2 axis in non‑small‑cell lung cancer

Cancer cells use aerobic glycolysis to sustain their proliferation. Long non‑coding RNA brain cytoplasmic RNA 1 (BCYRN1) has been reported to act as an oncogene in non‑small‑cell lung cancer (NSCLC). The present study investigated the role of BCYRN1 in NSCLC glycolysis. BCYRN1 expression was detected in NSCLC cells and tissues using reverse transcription‑quantitative PCR. The effect of BCYRN1 on aerobic glycolysis was examined by measuring NSCLC cell glucose catabolism and lactate synthesis. The relationships between BCYRN1 and microRNA (miR)‑149, and between miR‑149 and pyruvate kinase M1/2 (PKM2) were measured using a dual‑luciferase reporter assay. Cell proliferation and invasion were analyzed by the Cell Counting kit‑8 assay and the Matrigel invasion assay, respectively. High BCYRN1 expression was observed in NSCLC tissues and cells compared with the corresponding controls. BCYRN1 induced glycolysis and upregulated the expression levels of PKM2 in NSCLC cells. In addition, BCYRN1 regulated miR‑149 expression levels, and miR‑149 inhibitor rescued the effects of si‑BCYRN1 on glucose consumption and lactate production. miR‑149 knockdown significantly enhanced the expression of PKM2. Furthermore, PKM2 inhibition significantly reversed the effects of miR‑149 inhibitor on glucose catabolism and lactate synthesis. Furthermore, PKM2 was involved in NSCLC cell proliferation and invasion, and BCYRN1 knockdown and miR‑149 overexpression inhibited both processes. The present study suggested that BCYRN1 was involved in cell glycolysis, proliferation and invasion during NSCLC via regulating miR‑149 and PKM2.

Tanshinone IIA inhibits glucose metabolism leading to apoptosis in cervical cancer

Cancer requires aerobic glycolysis to supply the energy required for proliferation. Existing evidence has revealed that blocking glycolysis results in apoptosis of cancer cells. Tanshinone IIA (Tan IIA) is a diterpenoid naphthoquinone found in traditional Chinese medicine, Danshen (Salvia sp.). Tan IIA exhibits potential anticancer activity. However, its effect on cell viability of human cervical cancer cells and its mechanism are unknown. The aim of the present study was to determine the effect of Tan IIA on proliferation and glucose metabolism in cervical cancer cells. Cell viability was measured by MTT assay, apoptosis was determined using flow cytometry and glucose uptake, lactate production, and adenosine triphosphate content were measured to assess glucose metabolism. The expression of apoptosis‑associated proteins was detected by western blotting and the antitumor activity of Tan IIA in vivo was evaluated in cervical carcinoma‑bearing mice. The results revealed Tan IIA treatment resulted in a considerable reduction in the viability of SiHa cells. Tan IIA decreased the expression of HPV oncogenes E6 and E7, induced apoptosis and also decreased glycolysis by suppressing the activity of the intracellular AKT/mTOR and HIF‑1α. In vivo, treatment with Tan IIA resulted in a 72.7% reduction in tumor volume. The present study highlights the potential therapeutic value of Tan IIA, which functions by inducing apoptosis and may be associated with inhibition of glycolysis.

Apigenin and hesperidin augment the toxic effect of doxorubicin against HepG2 cells

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignancies, with an increasing incidence. Despite the fact that systematic chemotherapy with a doxorubicin provides only marginal improvements in survival of the HCC patients, the doxorubicin is being used in transarterial therapies or combined with the target drug - sorafenib. The aim of the study was to evaluate the effect of natural flavonoids on the cytotoxicity of the doxorubicin against human hepatocellular carcinoma cell line HepG2.

METHODS

The effect of apigenin and its glycosides - cosmosiin, rhoifolin; baicalein and its glycosides - baicalin as well as hesperetin and its glycosides - hesperidin on glycolytic genes expression of HepG2 cell line, morphology and cells' viability at the presence of doxorubicin have been tested. In an attempt to elucidate the mechanism of observed results, the fluorogenic probe for reactive oxygen species (ROS), the DNA oxidative damage, the lipid peroxidation and the double strand breaks were evaluated. To assess impact on the glycolysis pathway, the mRNA expression for a hexokinase 2 (HK2) and a lactate dehydrogenase A (LDHA) enzymes were measured. The results were analysed statistically with the one-way analysis of variance (ANOVA) and post hoc multiple comparisons.

RESULTS

The apigenin and the hesperidin revealed the strongest effect on the toxicity of doxorubicin. Both flavonoids simultaneously changed the expression of the glycolytic pathway genes - HK2 and LDHA, which play a key role in the Warburg effect. Although separate treatment with doxorubicin, apigenin and hesperidin led to a significant oxidative DNA damage and double strand breaks, simultaneous administration of doxorubicin and apigenin or hesperidin abolished these damage with the simultaneous increase in the doxorubicin toxicity.

CONCLUSION

The obtained results indicate the existence of a very effective cytotoxic mechanism in the HepG2 cells of the combined effect of doxorubicin and apigenin (or hesperidin), not related to the oxidative stress. To explain this synergy mechanism, further research is needed, The observed intensification of the cytotoxic effect of doxorubicin by this flavonoids may be a promising direction of the research on the therapy of hepatocellular carcinoma, especially in a chemoembolization.

MPC1 deficiency accelerates lung adenocarcinoma progression through the STAT3 pathway

Mitochondrial pyruvate carrier 1 (MPC1), a key factor that controls pyruvate transportation in the mitochondria, is known to be frequently dysregulated in tumor initiation and progression. However, the clinical relevance and potential molecular mechanisms of MPC1 in lung adenocarcinoma (LAC) progression remain to be illustrated. Herein, MPC1 was lowly expressed in LAC tissues and significantly associated with favorable survival of patients with LAC. Functionally, MPC1 markedly suppressed stemness, invasion, and migration in vitro and spreading growth of LAC cells in vivo. Further study revealed that MPC1 could interact with mitochondrial signal transducer and activator of transcription 3 (mito-STAT3), disrupting the distribution of STAT3 and reducing cytoplasmic signal transducer and activator of transcription 3 (cyto-STAT3) as well as its phosphorylation, while the activation of cyto-STAT3 by IL-6 reversed the attenuated malignant progression in MPC1-overexpression LAC cells. Collectively, we reveal that MPC1/STAT3 axis plays an important role in the progression of LAC, and our work may promote the development of new therapeutic strategies for LAC.

Metabolic reprogramming results in abnormal glycolysis in gastric cancer: a review

The Warburg effect in tumor cells involves the uptake of high levels of glucose, enhanced glycolysis, and the metabolism of pyruvate to lactic acid rather than oxidative phos-phorylation to generate energy under aerobic conditions. This effect is closely related to the occurrence, invasion, metastasis, drug resistance, and poor prognosis of gastric cancer (GC). Current research has further demonstrated that the Warburg effect in GC cells is not only mediated by the glycolysis pathway, but also includes roles for mitochondria, noncoding RNAs, and other proteins that do not directly regulate metabolism. As a result, changes in the glycolysis pathway not only lead to abnormal glucose metabolism, but they also affect mitochondrial functions, cellular processes such as apoptosis and cell cycle regulation, and the metabolism of lipids and amino acids. In this review, we discuss metabolic reprogramming in GC based on glycolysis, a possible link between glucose metabolism, lipid metabolism, and amino acid metabolism, and we clarify the role of mitochondria. We also examine recent studies of metabolic inhibitors in GC.