Increased adipocyte O2 consumption triggers HIF-1α, causing inflammation and insulin resistance in obesity.

Adipose tissue hypoxia and inflammation have been causally implicated in obesity-induced insulin resistance. Here, we report that, early in the course of high-fat diet (HFD) feeding and obesity, adipocyte respiration becomes uncoupled, leading to increased oxygen consumption and a state of relative adipocyte hypoxia. These events are sufficient to trigger HIF-1α induction, setting off the chronic adipose tissue inflammatory response characteristic of obesity. At the molecular level, these events involve saturated fatty acid stimulation of the adenine nucleotide translocase 2 (ANT2), an inner mitochondrial membrane protein, which leads to the uncoupled respiratory state. Genetic or pharmacologic inhibition of either ANT2 or HIF-1α can prevent or reverse these pathophysiologic events, restoring a state of insulin sensitivity and glucose tolerance. These results reveal the sequential series of events in obesity-induced inflammation and insulin resistance.

Monitoring Early Breast Cancer Response to Neoadjuvant Therapy Using H-Scan Ultrasound Imaging: Preliminary Preclinical Results.

OBJECTIVE: H-scan imaging is a new ultrasound technique used to visualize the relative size of acoustic scatterers. The purpose of this study was to evaluate the use of H-scan ultrasound imaging for monitoring early tumor response to neoadjuvant treatment using a preclinical breast cancer animal model. METHODS: Real-time H-scan ultrasound imaging was implemented on a programmable ultrasound scanner (Vantage 256; Verasonics Inc., Kirkland, WA) equipped with an L11-4v transducer. Bioluminescence and H-scan ultrasound was used to image luciferase-positive breast cancer-bearing mice at baseline and at 24, 48, and 168 hours after administration of a single dose of neoadjuvant (paclitaxel) or sham treatment. Animals were euthanized at 48 or 168 hours, and tumors underwent histologic processing to identify cancer cell proliferation and apoptosis. RESULTS: Baseline H-scan ultrasound images of control and therapy group tumors were comparable, but the latter exhibited significant changes over the 7-day study (P < .05). At termination, there was a marked difference between the H-scan ultrasound images of control and treated tumors (P < .05). Specifically, H-scan ultrasound images of treated tumors were more blue in hue than images obtained from control tumors. There was a significant linear correlation between the predominance of the blue hue found in the H-scan ultrasound images and intratumoral apoptotic activity (R2 > 0.40, P < .04). CONCLUSION: Preliminary preclinical results suggest that H-scan ultrasound imaging is a new and promising tissue characterization modality. H-scan ultrasound imaging may provide prognostic value when monitoring early tumor response to neoadjuvant treatment.

Targeting Hypoxia-Inducible Factor-1α/Pyruvate Dehydrogenase Kinase 1 Axis by Dichloroacetate Suppresses Bleomycin-induced Pulmonary Fibrosis.

Hypoxia has long been implicated in the pathogenesis of fibrotic diseases. Aberrantly activated myofibroblasts are the primary pathological driver of fibrotic progression, yet how various microenvironmental influences, such as hypoxia, contribute to their sustained activation and differentiation is poorly understood. As a defining feature of hypoxia is its impact on cellular metabolism, we sought to investigate how hypoxia-induced metabolic reprogramming affects myofibroblast differentiation and fibrotic progression, and to test the preclinical efficacy of targeting glycolytic metabolism for the treatment of pulmonary fibrosis. Bleomycin-induced pulmonary fibrotic progression was evaluated in two independent, fibroblast-specific, promoter-driven, hypoxia-inducible factor (Hif) 1A knockout mouse models and in glycolytic inhibitor, dichloroacetate-treated mice. Genetic and pharmacological approaches were used to explicate the role of metabolic reprogramming in myofibroblast differentiation. Hypoxia significantly enhanced transforming growth factor-ß-induced myofibroblast differentiation through HIF-1α, whereas overexpression of the critical HIF-1α-mediated glycolytic switch, pyruvate dehydrogenase kinase 1 (PDK1) was sufficient to activate glycolysis and potentiate myofibroblast differentiation, even in the absence of HIF-1α. Inhibition of the HIF-1α/PDK1 axis by genomic deletion of Hif1A or pharmacological inhibition of PDK1 significantly attenuated bleomycin-induced pulmonary fibrosis. Our findings suggest that HIF-1α/PDK1-mediated glycolytic reprogramming is a critical metabolic alteration that acts to promote myofibroblast differentiation and fibrotic progression, and demonstrate that targeting glycolytic metabolism may prove to be a potential therapeutic strategy for the treatment of pulmonary fibrosis.

Glucose Transporter 1 Gene Variants Predict the Prognosis of Patients with Early-Stage Non-small Cell Lung Cancer.

BACKGROUND: This study was conducted to investigate whether polymorphisms of glucose transporter 1 (GLUT1) gene are associated with the prognosis of patients with non-small cell lung cancer (NSCLC) after surgical resection. METHODS: Five single nucleotide polymorphisms (SNPs) in GLUT1 were investigated in a total of 354 patients with NSCLC who underwent curative surgery. The association of the SNPs with patients' survival was analyzed. RESULTS: Among the five SNPs investigated, two SNPs (GLUT1 rs3820589T > A and rs4658G > C) were significantly associated with OS in multivariate analyses. GLUT1 rs3820589T > A was associated with significantly better OS (adjusted hazard ratio [aHR] = 0.57, 95% confidence interval [CI] = 0.34-0.94, P = 0.03, under dominant model), and rs4658G > C was associated with significantly worse OS (aHR = 1.91, 95% CI = 1.09-3.33, P = 0.02, under recessive model). In the stratified analysis by tumor histology, the effect of these SNPs on OS was only significant in squamous cell carcinoma but not in adenocarcinoma. When the two SNPs were combined, OS decreased as the number of bad genotypes increased (Ptrend = 4 × 10-3). CONCLUSIONS: This study suggests that genetic variation in GLUT1 may be useful in predicting survival of patients with early stage NSCLC.

Differential activation and antagonistic function of HIF-{alpha} isoforms in macrophages are essential for NO homeostasis.

Hypoxic response and inflammation both involve the action of the hypoxia-inducible transcription factors HIF-1alpha and HIF-2alpha. Previous studies have revealed that both HIF-alpha proteins are in a number of aspects similarly regulated post-translationally. However, the functional interrelationship of these two isoforms remains largely unclear. The polarization of macrophages controls functionally divergent processes; one of these is nitric oxide (NO) production, which in turn is controlled in part by HIF factors. We show here that the HIF-alpha isoforms can be differentially activated: HIF-1alpha is induced by Th1 cytokines in M1 macrophage polarization, whereas HIF-2alpha is induced by Th2 cytokines during an M2 response. This differential response was most evident in polarized macrophages through HIF-alpha isoform-specific regulation of the inducible NO synthase gene by HIF-1alpha, and the arginase1 gene by HIF-2alpha. In silico modeling predicted that regulation of overall NO availability is due to differential regulation of HIF-1alpha versus HIF-2alpha, acting to, respectively, either increase or suppress NO synthesis. An in vivo model of endotoxin challenge confirmed this; thus, these studies reveal that the two homologous transcription factors, HIF-1alpha and HIF-2alpha, can have physiologically antagonistic functions, but that their antiphase regulation allows them to coordinately regulate NO production in a cytokine-induced and transcription-dependent fashion.

HIF isoforms in the skin differentially regulate systemic arterial pressure.

Vascular flow through tissues is regulated via a number of homeostatic mechanisms. Localized control of tissue blood flow, or autoregulation, is a key factor in regulating tissue perfusion and oxygenation. We show here that the net balance between two hypoxia-inducible factor (HIF) transcription factor isoforms, HIF-1α and HIF-2α, is an essential mechanism regulating both local and systemic blood flow in the skin of mice. We also show that balance of HIF isoforms in keratinocyte-specific mutant mice affects thermal adaptation, exercise capacity, and systemic arterial pressure. The two primary HIF isoforms achieve these effects in opposing ways that are associated with HIF isoform regulation of nitric oxide production. We also show that a correlation exists between altered levels of HIF isoforms in the skin and the degree of idiopathic hypertension in human subjects. Thus, the balance between HIF-1α and HIF-2α expression in keratinocytes is a control element of both tissue perfusion and systemic arterial pressure, with potential implications in human hypertension.

GATA-3 and the regulation of the mammary luminal cell fate.

The GATA family of transcription factors plays essential roles in the specification and maintenance of differentiated cell types. GATA-3 was identified in a microarray screen of the mouse mammary gland as the most highly expressed transcription factor in the mammary epithelium and is expressed exclusively in the luminal epithelial cell population. Targeted deletion of GATA-3 in mammary glands leads to profound defects in mammary development and inability to specify and maintain the luminal cell fate in the adult mouse. In breast cancer, GATA-3 has emerged as a strong predictor of tumor differentiation, estrogen-receptor status, and clinical outcome. GATA-3 maintains tumor differentiation and suppresses tumor dissemination in a mouse model of breast cancer. This review explores our current understanding of GATA-3 signaling in luminal cell differentiation, both in mammary development and breast cancer.

Heme Sequestration Effectively Suppresses the Development and Progression of Both Lung Adenocarcinoma and Squamous Cell Carcinoma.

Lung adenocarcinoma (ADC) and squamous cell carcinoma (SCC) are two most common subtypes of lung cancer. Here, to identify new, targetable molecular properties of both subtypes, we monitored changes in the levels of heme- and oxidative phosphorylation (OXPHOS)-related proteins during lung tumorigenesis. Heme is a central molecule for oxidative metabolism and ATP generation via OXPHOS. Notably, both lung ADC and SCC tumors can be induced in the genetically engineered KLLuc mouse model harboring the G12D Kras mutation and a conditional Lkb1 knockout. We found that the levels of the rate-limiting heme synthesis enzyme ALAS1 and uptake protein SLC48A1, along with OXPHOS complex subunits, progressively increased as lung tumorigenesis advanced. Our data demonstrated that elevated levels of heme- and OXPHOS-related proteins were associated with both ADC and SCC. Importantly, treatment of KLLuc mice with a heme-sequestering protein, HeSP2, that inhibits heme uptake in tumor cells effectively arrested lung tumor progression, and both ADC and SCC tumors were strongly suppressed. Additionally, HeSP2 effectively suppressed the growth of both SCC and ADC tumor xenografts in NOD/SCID mice. Further analyses indicated that HeSP2 effectively diminished OXPHOS in both ADC and SCC, reduced angiogenesis, alleviated tumor hypoxia, and suppressed cell proliferation. These results show that the advancing of lung tumorigenesis requires progressive increase in cellular heme synthesis and uptake, leading to intensified OXPHOS activity and ATP generation and promoting aggressive tumorigenic functions. IMPLICATIONS: Heme sequestration is an effective strategy for the suppression of both ADC and SCC tumor initiation and development.

HIF-1-mediated expression of pyruvate dehydrogenase kinase: a metabolic switch required for cellular adaptation to hypoxia.

Activation of glycolytic genes by HIF-1 is considered critical for metabolic adaptation to hypoxia through increased conversion of glucose to pyruvate and subsequently to lactate. We found that HIF-1 also actively suppresses metabolism through the tricarboxylic acid cycle (TCA) by directly trans-activating the gene encoding pyruvate dehydrogenase kinase 1 (PDK1). PDK1 inactivates the TCA cycle enzyme, pyruvate dehydrogenase (PDH), which converts pyruvate to acetyl-CoA. Forced PDK1 expression in hypoxic HIF-1alpha null cells increases ATP levels, attenuates hypoxic ROS generation, and rescues these cells from hypoxia-induced apoptosis. These studies reveal a hypoxia-induced metabolic switch that shunts glucose metabolites from the mitochondria to glycolysis to maintain ATP production and to prevent toxic ROS production.

Oxidative Stress and the Intersection of Oncogenic Signaling and Metabolism in Squamous Cell Carcinomas.

Squamous cell carcinomas (SCCs) arise from both stratified squamous and non-squamous epithelium of diverse anatomical sites and collectively represent one of the most frequent solid tumors, accounting for more than one million cancer deaths annually. Despite this prevalence, SCC patients have not fully benefited from recent advances in molecularly targeted therapy or immunotherapy. Rather, decades old platinum-based or radiation regimens retaining limited specificity to the unique characteristics of SCC remain first-line treatment options. Historically, a lack of a consolidated perspective on genetic aberrations driving oncogenic transformation and other such factors essential for SCC pathogenesis and intrinsic confounding cellular heterogeneity in SCC have contributed to a critical dearth in effective and specific therapies. However, emerging evidence characterizing the distinct genomic, epigenetic, and metabolic landscapes of SCC may be elucidating unifying features in a seemingly heterogeneous disease. In this review, by describing distinct metabolic alterations and genetic drivers of SCC revealed by recent studies, we aim to establish a conceptual framework for a previously unappreciated network of oncogenic signaling, redox perturbation, and metabolic reprogramming that may reveal targetable vulnerabilities at their intersection.

Epidemiological characteristics of a COVID-19 outbreak caused by religious activities in Daegu, Korea.

OBJECTIVES: A coronavirus disease 2019 (COVID-19) outbreak triggered by religious activities occurred in Daegu, Korea in February 2020. This outbreak spread rapidly to the community through high-risk groups. This study describes the characteristics of COVID-19 cases based on S religious group membership and summarizes the Daegu municipal government's processes and responses to control the outbreak. METHODS: The epidemiological characteristics of confirmed cases were obtained through basic and in-depth epidemiological surveys. General characteristics, the proportion of asymptomatic cases, the case-fatality rate, and the time-to-event within each group were presented after stratifying confirmed cases according to S religious group membership. RESULTS: Overall, 7,008 COVID-19 cases were confirmed in Daegu from February 18, 2020 to June 30, 2020, and 61.5% (n= 4,309) were S religious group members. Compared with non-members, members had a higher proportion of female (p< 0.001) and younger age (p< 0.001), as well as lower disease prevalence. At the time of the investigation, 38.4% of cases in members were asymptomatic versus 23.7% of cases in non-members (p< 0.001). The case-fatality rate of non-members aged ≥ 60 years was significantly higher than that of members (p< 0.001). Compared with non-members, members had longer intervals from symptom onset to diagnosis (p< 0.001) and from diagnosis to admission (p< 0.001), and a shorter interval from admission to discharge (p< 0.001). CONCLUSIONS: The epidemiological features of S religious group members, including the proportion of asymptomatic cases, case-fatality rate, and time-to-event, differed from non-members. The Daegu authorities prevented further COVID-19 spread through immediate isolation and active screening tests of all S religious group members.

Hypoxia-inducible factor 1 and dysregulated c-Myc cooperatively induce vascular endothelial growth factor and metabolic switches hexokinase 2 and pyruvate dehydrogenase kinase 1.

Hypoxia is a pervasive microenvironmental factor that affects normal development as well as tumor progression. In most normal cells, hypoxia stabilizes hypoxia-inducible transcription factors (HIFs), particularly HIF-1, which activates genes involved in anaerobic metabolism and angiogenesis. As hypoxia signals a cellular deprivation state, HIF-1 has also been reported to counter the activity of MYC, which encodes a transcription factor that drives cell growth and proliferation. Since many human cancers express dysregulated MYC, we sought to determine whether HIF-1 would in fact collaborate with dysregulated MYC rather countering its function. Here, using the P493-6 Burkitt's lymphoma model with an inducible MYC, we demonstrate that HIF-1 cooperates with dysregulated c-Myc to promote glycolysis by induction of hexokinase 2, which catalyzes the first step of glycolysis, and pyruvate dehydrogenase kinase 1, which inactivates pyruvate dehydrogenase and diminishes mitochondrial respiration. We also found the collaborative induction of vascular endothelial growth factor (VEGF) by HIF-1 and dysregulated c-Myc. This study reports the previously unsuspected collaboration between HIF-1 and dysregulated MYC and thereby provides additional insights into the regulation of VEGF and the Warburg effect, which describes the propensity for cancer cells to convert glucose to lactate.

Multifaceted roles of glycolytic enzymes.

Although glycolysis is a biochemical pathway that evolved under ancient anaerobic terrestrial conditions, recent studies have provided evidence that some glycolytic enzymes are more complicated, multifaceted proteins rather than simple components of the glycolytic pathway. These glycolytic enzymes have acquired additional non-glycolytic functions in transcriptional regulation [hexokinase (HK)-2, lactate dehydrogenase A, glyceraldehyde-3-phosphate dehydrogenase (GAPD) and enolase 1], stimulation of cell motility (glucose-6-phosphate isomerase) and the regulation of apoptosis (glucokinase, HK and GAPD). The existence of multifaceted roles of glycolytic proteins suggests that links between metabolic sensors and transcription are established directly through enzymes that participate in metabolism. These roles further underscore the need to consider the non-enzymatic functions of enzymes in proteomic studies of cells and tissues.

Stromal Hedgehog pathway activation by IHH suppresses lung adenocarcinoma growth and metastasis by limiting reactive oxygen species.

Activation of the Hedgehog (Hh) signaling pathway by mutations within its components drives the growth of several cancers. However, the role of Hh pathway activation in lung cancers has been controversial. Here, we demonstrate that the canonical Hh signaling pathway is activated in lung stroma by Hh ligands secreted from transformed lung epithelia. Genetic deletion of Shh, the primary Hh ligand expressed in the lung, in KrasG12D/+;Trp53fl/fl autochthonous murine lung adenocarcinoma had no effect on survival. Early abrogation of the pathway by an anti-SHH/IHH antibody 5E1 led to significantly worse survival with increased tumor and metastatic burden. Loss of IHH, another Hh ligand, by in vivo CRISPR led to more aggressive tumor growth suggesting that IHH, rather than SHH, activates the pathway in stroma to drive its tumor suppressive effects-a novel role for IHH in the lung. Tumors from mice treated with 5E1 had decreased blood vessel density and increased DNA damage suggestive of reactive oxygen species (ROS) activity. Treatment of KrasG12D/+;Trp53fl/fl mice with 5E1 and N-acetylcysteine, as a ROS scavenger, decreased tumor DNA damage, inhibited tumor growth and prolonged mouse survival. Thus, IHH induces stromal activation of the canonical Hh signaling pathway to suppress tumor growth and metastases, in part, by limiting ROS activity.

Activation of transferrin receptor 1 by c-Myc enhances cellular proliferation and tumorigenesis.

Overexpression of transferrin receptor 1 (TFRC1), a major mediator of iron uptake in mammalian cells, is a common feature of human malignancies. Therapeutic strategies designed to interfere with tumor iron metabolism have targeted TFRC1. The c-Myc oncogenic transcription factor stimulates proliferation and growth by activating thousands of target genes. Here we demonstrate that TFRC1 is a critical downstream target of c-Myc. Using in vitro and in vivo models of B-cell lymphoma, we show that TFRC1 expression is activated by c-Myc. Chromatin immunoprecipitation experiments reveal that c-Myc directly binds a conserved region of TFRC1. In light of these findings, we sought to determine whether TFRC1 is required for c-Myc-mediated cellular proliferation and cell size control. TFRC1 inhibition decreases cellular proliferation and results in G1 arrest without affecting cell size. Consistent with these findings, expression profiling reveals that TFRC1 depletion alters expression of genes that regulate the cell cycle. Furthermore, enforced TFRC1 expression confers a growth advantage to cells and significantly enhances the rate of c-Myc-mediated tumor formation in vivo. These findings provide a molecular basis for increased TFRC1 expression in human tumors, illuminate the role of TFRC1 in the c-Myc target gene network, and support strategies that target TFRC1 for cancer therapy.

Macrophage hypoxia signaling regulates cardiac fibrosis via Oncostatin M.

The fibrogenic response in tissue-resident fibroblasts is determined by the balance between activation and repression signals from the tissue microenvironment. While the molecular pathways by which transforming growth factor-1 (TGF-ß1) activates pro-fibrogenic mechanisms have been extensively studied and are recognized critical during fibrosis development, the factors regulating TGF-ß1 signaling are poorly understood. Here we show that macrophage hypoxia signaling suppresses excessive fibrosis in a heart via oncostatin-m (OSM) secretion. During cardiac remodeling, Ly6Chi monocytes/macrophages accumulate in hypoxic areas through a hypoxia-inducible factor (HIF)-1α dependent manner and suppresses cardiac fibroblast activation. As an underlying molecular mechanism, we identify OSM, part of the interleukin 6 cytokine family, as a HIF-1α target gene, which directly inhibits the TGF-ß1 mediated activation of cardiac fibroblasts through extracellular signal-regulated kinase 1/2-dependent phosphorylation of the SMAD linker region. These results demonstrate that macrophage hypoxia signaling regulates fibroblast activation through OSM secretion in vivo.

p63 and SOX2 Dictate Glucose Reliance and Metabolic Vulnerabilities in Squamous Cell Carcinomas.

Squamous cell carcinoma (SCC), a malignancy arising across multiple anatomical sites, is responsible for significant cancer mortality due to insufficient therapeutic options. Here, we identify exceptional glucose reliance among SCCs dictated by hyperactive GLUT1-mediated glucose influx. Mechanistically, squamous lineage transcription factors p63 and SOX2 transactivate the intronic enhancer cluster of SLC2A1. Elevated glucose influx fuels generation of NADPH and GSH, thereby heightening the anti-oxidative capacity in SCC tumors. Systemic glucose restriction by ketogenic diet and inhibiting renal glucose reabsorption with SGLT2 inhibitor precipitate intratumoral oxidative stress and tumor growth inhibition. Furthermore, reduction of blood glucose lowers blood insulin levels, which suppresses PI3K/AKT signaling in SCC cells. Clinically, we demonstrate a robust correlation between blood glucose concentration and worse survival among SCC patients. Collectively, this study identifies the exceptional glucose reliance of SCC and suggests its candidacy as a highly vulnerable cancer type to be targeted by systemic glucose restriction.

Pyruvate Dehydrogenase Kinase Is a Metabolic Checkpoint for Polarization of Macrophages to the M1 Phenotype.

Metabolic reprogramming during macrophage polarization supports the effector functions of these cells in health and disease. Here, we demonstrate that pyruvate dehydrogenase kinase (PDK), which inhibits the pyruvate dehydrogenase-mediated conversion of cytosolic pyruvate to mitochondrial acetyl-CoA, functions as a metabolic checkpoint in M1 macrophages. Polarization was not prevented by PDK2 or PDK4 deletion but was fully prevented by the combined deletion of PDK2 and PDK4; this lack of polarization was correlated with improved mitochondrial respiration and rewiring of metabolic breaks that are characterized by increased glycolytic intermediates and reduced metabolites in the TCA cycle. Genetic deletion or pharmacological inhibition of PDK2/4 prevents polarization of macrophages to the M1 phenotype in response to inflammatory stimuli (lipopolysaccharide plus IFN-γ). Transplantation of PDK2/4-deficient bone marrow into irradiated wild-type mice to produce mice with PDK2/4-deficient myeloid cells prevented M1 polarization, reduced obesity-associated insulin resistance, and ameliorated adipose tissue inflammation. A novel, pharmacological PDK inhibitor, KPLH1130, improved high-fat diet-induced insulin resistance; this was correlated with a reduction in the levels of pro-inflammatory markers and improved mitochondrial function. These studies identify PDK2/4 as a metabolic checkpoint for M1 phenotype polarization of macrophages, which could potentially be exploited as a novel therapeutic target for obesity-associated metabolic disorders and other inflammatory conditions.

Myc stimulates nuclearly encoded mitochondrial genes and mitochondrial biogenesis.

Although several genes involved in mitochondrial function are direct Myc targets, the role of Myc in mitochondrial biogenesis has not been directly established. We determined the effects of ectopic Myc expression or the loss of Myc on mitochondrial biogenesis. Induction of Myc in P493-6 cells resulted in increased oxygen consumption and mitochondrial mass and function. Conversely, compared to wild-type Myc fibroblasts, Myc null rat fibroblasts have diminished mitochondrial mass and decreased number of normal mitochondria. Reconstitution of Myc expression in Myc null fibroblasts partially restored mitochondrial mass and function and normal-appearing mitochondria. Concordantly, we also observed in primary hepatocytes that acute deletion of floxed murine Myc by Cre recombinase resulted in diminished mitochondrial mass in primary hepatocytes. Our microarray analysis of genes responsive to Myc in human P493-6 B lymphocytes supports a role for Myc in mitochondrial biogenesis, since genes involved in mitochondrial structure and function are overrepresented among the Myc-induced genes. In addition to the known direct binding of Myc to many genes involved in mitochondrial structure and function, we found that Myc binds the TFAM gene, which encodes a key transcriptional regulator and mitochondrial DNA replication factor, both in P493-6 lymphocytes with high ectopic MYC expression and in serum-stimulated primary human 2091 fibroblasts with induced endogenous MYC. These observations support a pivotal role for Myc in regulating mitochondrial biogenesis.

Cancer's molecular sweet tooth and the Warburg effect.

More than 80 years ago, the renowned biochemist Otto Warburg described how cancer cells avidly consume glucose and produce lactic acid under aerobic conditions. Recent studies arguing that cancer cells benefit from this phenomenon, termed the Warburg effect, have renewed discussions about its exact role as cause, correlate, or facilitator of cancer. Molecular advances in this area may reveal tactics to exploit the cancer cell's "sweet tooth" for cancer therapy.