Metabolic Alterations in Aging Macrophages: Ingredients for Inflammaging?

Aging is a complex process with an impact on essentially all organs. Declined cellular repair causes increased damage at genomic and proteomic levels upon aging. This can lead to systemic changes in metabolism and pro-inflammatory cytokine production, resulting in low-grade inflammation, or 'inflammaging'. Tissue macrophages, gatekeepers of parenchymal homeostasis and integrity, are prime inflammatory cytokine producers, as well as initiators and regulators of inflammation. In this opinion piece, we summarize intrinsic alterations in macrophage phenotype and function with age. We propose that alternatively activated macrophages (M2-like), which are yet pro-inflammatory, can accumulate in tissues and promote inflammaging. Age-related increases in endoplasmic reticulum stress and mitochondrial dysfunction might be cell-intrinsic forces driving this unusual phenotype.

Peripheral mitochondrial function correlates with clinical severity in idiopathic Parkinson's disease.

BACKGROUND: Parkinson's disease is an intractable disorder with heterogeneous clinical presentation that may reflect different underlying pathogenic mechanisms. Surrogate indicators of pathogenic processes correlating with clinical measures may assist in better patient stratification. Mitochondrial function, which is impaired in and central to PD pathogenesis, may represent one such surrogate indicator. METHODS: Mitochondrial function was assessed by respirometry experiment in fibroblasts derived from idiopathic patients (n = 47) in normal conditions and in experimental settings that do not permit glycolysis and therefore force energy production through mitochondrial function. Respiratory parameters and clinical measures were correlated with bivariate analysis. Machine-learning-based classification and regression trees were used to classify patients on the basis of biochemical and clinical measures. The effects of mitochondrial respiration on α-synuclein stress were assessed monitoring the protein phosphorylation in permitting versus restrictive glycolysis conditions. RESULTS: Bioenergetic properties in peripheral fibroblasts correlate with clinical measures in idiopathic patients, and the correlation is stronger with predominantly nondopaminergic signs. Bioenergetic analysis under metabolic stress, in which energy is produced solely by mitochondria, shows that patients' fibroblasts can augment respiration, therefore indicating that mitochondrial defects are reversible. Forcing energy production through mitochondria, however, favors α-synuclein stress in different cellular experimental systems. Machine-learning-based classification identified different groups of patients in which increasing disease severity parallels higher mitochondrial respiration. CONCLUSION: The suppression of mitochondrial activity in PD may be an adaptive strategy to cope with concomitant pathogenic factors. Moreover, mitochondrial measures in fibroblasts are potential peripheral biomarkers to follow disease progression. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Brain Radiation Information Data Exchange (BRIDE): integration of experimental data from low-dose ionising radiation research for pathway discovery.

BACKGROUND: The underlying molecular processes representing stress responses to low-dose ionising radiation (LDIR) in mammals are just beginning to be understood. In particular, LDIR effects on the brain and their possible association with neurodegenerative disease are currently being explored using omics technologies. RESULTS: We describe a light-weight approach for the storage, analysis and distribution of relevant LDIR omics datasets. The data integration platform, called BRIDE, contains information from the literature as well as experimental information from transcriptomics and proteomics studies. It deploys a hybrid, distributed solution using both local storage and cloud technology. CONCLUSIONS: BRIDE can act as a knowledge broker for LDIR researchers, to facilitate molecular research on the systems biology of LDIR response in mammals. Its flexible design can capture a range of experimental information for genomics, epigenomics, transcriptomics, and proteomics. The data collection is available at: .

Neonatal Irradiation Leads to Persistent Proteome Alterations Involved in Synaptic Plasticity in the Mouse Hippocampus and Cortex.

Recent epidemiological data indicate that radiation doses as low as those used in computer tomography may result in long-term neurocognitive side effects. The aim of this study was to elucidate long-term molecular alterations related to memory formation in the brain after low and moderate doses of γ radiation. Female C57BL/6J mice were irradiated on postnatal day 10 with total body doses of 0.1, 0.5, or 2.0 Gy; the control group was sham-irradiated. The proteome analysis of hippocampus, cortex, and synaptosomes isolated from these brain regions indicated changes in ephrin-related, RhoGDI, and axonal guidance signaling. Immunoblotting and miRNA-quantification demonstrated an imbalance in the synapse morphology-related Rac1-Cofilin pathway and long-term potentiation-related cAMP response element-binding protein (CREB) signaling. Proteome profiling also showed impaired oxidative phosphorylation, especially in the synaptic mitochondria. This was accompanied by an early (4 weeks) reduction of mitochondrial respiration capacity in the hippocampus. Although the respiratory capacity was restored by 24 weeks, the number of deregulated mitochondrial complex proteins was increased at this time. All observed changes were significant at doses of 0.5 and 2.0 Gy but not at 0.1 Gy. This study strongly suggests that ionizing radiation at the neonatal state triggers persistent proteomic alterations associated with synaptic impairment.

Low-dose ionizing radiation rapidly affects mitochondrial and synaptic signaling pathways in murine hippocampus and cortex.

The increased use of radiation-based medical imaging methods such as computer tomography is a matter of concern due to potential radiation-induced adverse effects. Efficient protection against such detrimental effects has not been possible due to inadequate understanding of radiation-induced alterations in signaling pathways. The aim of this study was to elucidate the molecular mechanisms behind learning and memory deficits after acute low and moderate doses of ionizing radiation. Female C57BL/6J mice were irradiated on postnatal day 10 (PND10) with gamma doses of 0.1 or 0.5 Gy. This was followed by evaluation of the cellular proteome, pathway-focused transcriptome, and neurological development/disease-focused miRNAome of hippocampus and cortex 24 h postirradiation. Our analysis showed that signaling pathways related to mitochondrial and synaptic functions were changed by acute irradiation. This may lead to reduced mitochondrial function paralleled by enhanced number of dendritic spines and neurite outgrowth due to elevated long-term potentiation, triggered by increased phosphorylated CREB. This was predominately observed in the cortex at 0.1 and 0.5 Gy and in the hippocampus only at 0.5 Gy. Moreover, a radiation-induced increase in the expression of several neural miRNAs associated with synaptic plasticity was found. The early changes in signaling pathways related to memory formation may be associated with the acute neurocognitive side effects in patients after brain radiotherapy but might also contribute to late radiation-induced cognitive injury.

Defects in mitochondrial clearance predispose human monocytes to interleukin-1ß hypersecretion.

Most hereditary periodic fever syndromes are mediated by deregulated IL-1ß secretion. The generation of mature IL-1ß requires two signals: one that induces synthesis of inflammasome components and substrates and a second that activates inflammasomes. The mechanisms that mediate autoinflammation in mevalonate kinase deficiency, a periodic fever disease characterized by a block in isoprenoid biosynthesis, are poorly understood. In studying the effects of isoprenoid shortage on IL-1 ß generation, we identified a new inflammasome activation signal that originates from defects in autophagy. We find that hypersecretion of IL-1ß and IL-18 requires reactive oxygen species and is associated with an oxidized redox status of monocytes but not lymphocytes. IL-1ß hypersecretion by monocytes involves decreased mitochondrial stability, release of mitochondrial content into the cytosol and attenuated autophagosomal degradation. Defective autophagy, as established by ATG7 knockdown, results in prolonged cytosolic retention of damaged mitochondria and increased IL-1ß secretion. Finally, activation of autophagy in healthy but not mevalonate kinase deficiency patient cells reduces IL-1ß secretion. Together, these results indicate that defective autophagy can prime monocytes for mitochondria-mediated NLRP3 inflammasome activation, thereby contributing to hypersecretion of IL-1ß in mevalonate kinase deficiency.

Direct activating effects of adrenocorticotropic hormone (ACTH) on brown adipose tissue are attenuated by corticosterone.

Brown adipose tissue (BAT) and brown-like cells in white adipose tissue (WAT) can dissipate energy through thermogenesis, a process mediated by uncoupling protein 1 (UCP1). We investigated whether stress hormones ACTH and corticosterone contribute to BAT activation and browning of WAT. ACTH and corticosterone were studied in male mice exposed to 4 or 23°C for 24 h. Direct effects were studied in T37i mouse brown adipocytes and primary cultured murine BAT and inguinal WAT (iWAT) cells. In vivo effects were studied using (18)F-deoxyglucose positron emission tomography. Cold exposure doubled serum ACTH concentrations (P=0.03) and fecal corticosterone excretion (P=0.008). In T37i cells, ACTH dose-dependently increased Ucp1 mRNA (EC50=1.8 nM) but also induced Ucp1 protein content 88% (P=0.02), glycerol release 32% (P=0.03) and uncoupled respiration 40% (P=0.003). In cultured BAT and iWAT, ACTH elevated Ucp1 mRNA by 3-fold (P=0.03) and 3.7-fold (P=0.01), respectively. In T37i cells, corticosterone prevented induction of Ucp1 mRNA and Ucp1 protein by both ACTH and norepinephrine in a glucocorticoid receptor (GR)-dependent fashion. ACTH and GR antagonist RU486 independently doubled BAT (18)F-deoxyglucose uptake (P=0.0003 and P=0.004, respectively) in vivo. Our results show that ACTH activates BAT and browning of WAT while corticosterone counteracts this.

Mitochondrial DNA damage: molecular marker of vulnerable nigral neurons in Parkinson's disease.

DNA damage can cause (and result from) oxidative stress and mitochondrial impairment, both of which are implicated in the pathogenesis of Parkinson's disease (PD). We therefore examined the role of mitochondrial DNA (mtDNA) damage in human postmortem brain tissue and in in vivo and in vitro models of PD, using a newly adapted histochemical assay for abasic sites and a quantitative polymerase chain reaction (QPCR)-based assay. We identified the molecular identity of mtDNA damage to be apurinic/apyrimidinic (abasic) sites in substantia nigra dopamine neurons, but not in cortical neurons from postmortem PD specimens. To model the systemic mitochondrial impairment of PD, rats were exposed to the pesticide rotenone. After rotenone treatment that does not cause neurodegeneration, abasic sites were visualized in nigral neurons, but not in cortex. Using a QPCR-based assay, a single rotenone dose induced mtDNA damage in midbrain neurons, but not in cortical neurons; similar results were obtained in vitro in cultured neurons. Importantly, these results indicate that mtDNA damage is detectable prior to any signs of degeneration - and is produced selectively in midbrain neurons under conditions of mitochondrial impairment. The selective vulnerability of midbrain neurons to mtDNA damage was not due to differential effects of rotenone on complex I since rotenone suppressed respiration equally in midbrain and cortical neurons. However, in response to complex I inhibition, midbrain neurons produced more mitochondrial H2O2 than cortical neurons. We report selective mtDNA damage as a molecular marker of vulnerable nigral neurons in PD and suggest that this may result from intrinsic differences in how these neurons respond to complex I defects. Further, the persistence of abasic sites suggests an ineffective base excision repair response in PD.

Orthogonal analysis of mitochondrial function in Parkinson's disease patients.

The etiopathology of Parkinson's disease has been associated with mitochondrial defects at genetic, laboratory, epidemiological, and clinical levels. These converging lines of evidence suggest that mitochondrial defects are systemic and causative factors in the pathophysiology of PD, rather than being mere correlates. Understanding mitochondrial biology in PD at a granular level is therefore crucial from both basic science and translational perspectives. In a recent study, we investigated mitochondrial alterations in fibroblasts obtained from PD patients assessing mitochondrial function in relation to clinical measures. Our findings demonstrated that the magnitude of mitochondrial alterations parallels disease severity. In this study, we extend these investigations to blood cells and dopamine neurons derived from induced pluripotent stem cells reprogrammed from PD patients. To overcome the inherent metabolic heterogeneity of blood cells, we focused our analyses on metabolically homogeneous, accessible, and expandable erythroblasts. Our results confirm the presence of mitochondrial anomalies in erythroblasts and induced dopamine neurons. Consistent with our previous findings in fibroblasts, we observed that mitochondrial alterations are reversible, as evidenced by enhanced mitochondrial respiration when PD erythroblasts were cultured in a galactose medium that restricts glycolysis. This observation indicates that suppression of mitochondrial respiration may constitute a protective, adaptive response in PD pathogenesis. Notably, this effect was not observed in induced dopamine neurons, suggesting their distinct bioenergetic behavior. In summary, we provide additional evidence for the involvement of mitochondria in the disease process by demonstrating mitochondrial abnormalities in additional cell types relevant to PD. These findings contribute to our understanding of PD pathophysiology and may have implications for the development of novel biomarkers and therapeutic strategies.

Thiol oxidation and altered NR2B/NMDA receptor functions in in vitro and in vivo pilocarpine models: implications for epileptogenesis.

Hippocampal sclerosis, the main pathological sign of chronic temporal lobe epilepsy (TLE), is associated with oxidative injury, altered N-methyl d-aspartate receptor (NMDAR) stoichiometry, and loss of hippocampal neurons. However, the mechanisms that drive the chronic progression of TLE remain elusive. Our previous studies have shown that NADPH oxidase activation and ERK 1/2 phosphorylation are required for the up-regulation of the predominantly pre-synaptic NR2B subunit auto-receptor in both in vitro and in vivo pilocarpine (PILO) models of TLE. To provide further understanding of the cellular responses during the early-stages of hyper excitability, we investigated the role of oxidative damage and altered NR2B functions. In rat primary hippocampal cultures, we found that N-acetylcysteine (NAC) prevented PILO-mediated thiol oxidation, apoptosis, cell death and NR2B subunit over-expression. Interestingly, NAC did not block thiol oxidation when added to the neurons 6h after the PILO exposure, suggesting that disulfide formation could rapidly become an irreversible phenomenon. Moreover, NAC pre-treatment did not prevent PILO-induced NR2A subunit over-expression, a critical event in hippocampal sclerosis. Pre-treatment with the highly specific NR2B subunit inhibitor, ifenprodil, partially decreased PILO-mediated thiol oxidation and was not effective in preventing apoptosis and cell death. However, if acutely administered 48h after PILO exposure, ifenprodil blocked glutamate-induced aberrant calcium influx, suggesting the crucial role of NR2B over-expression in triggering neuronal hyper-excitability. Furthermore, ifenprodil treatment was able to prevent NR2A subunit over-expression by means of ERK1/2 phosphorylation. Our findings indicate oxidative stress and NR2B/NMDA signaling as promising therapeutic targets for co-treatments aimed to prevent chronic epilepsy following the seizure onset.

Embryonic mouse blood flow and oxygen correlate with early pancreatic differentiation.

The mammalian embryo represents a fundamental paradox in biology. Its location within the uterus, especially early during development when embryonic cardiovascular development and placental blood flow are not well-established, leads to an obligate hypoxic environment. Despite this hypoxia, the embryonic cells are able to undergo remarkable growth, morphogenesis, and differentiation. Recent evidence suggests that embryonic organ differentiation, including pancreatic ß-cells, is tightly regulated by oxygen levels. Since a major determinant of oxygen tension in mammalian embryos after implantation is embryonic blood flow, here we used a novel survivable in utero intracardiac injection technique to deliver a vascular tracer to living mouse embryos. Once injected, the embryonic heart could be visualized to continue contracting normally, thereby distributing the tracer specifically only to those regions where embryonic blood was flowing. We found that the embryonic pancreas early in development shows a remarkable paucity of blood flow and that the presence of blood flow correlates with the differentiation state of the developing pancreatic epithelial cells in the region of the blood flow.

Corrigendum: The use of progeroid DNA repair-deficient mice for assessing anti-aging compounds, illustrating the benefits of nicotinamide riboside.

[This corrects the article DOI: 10.3389/fragi.2022.1005322.].

The use of progeroid DNA repair-deficient mice for assessing anti-aging compounds, illustrating the benefits of nicotinamide riboside.

Despite efficient repair, DNA damage inevitably accumulates with time affecting proper cell function and viability, thereby driving systemic aging. Interventions that either prevent DNA damage or enhance DNA repair are thus likely to extend health- and lifespan across species. However, effective genome-protecting compounds are largely lacking. Here, we use Ercc1 Δ/- and Xpg -/- DNA repair-deficient mutants as two bona fide accelerated aging mouse models to test propitious anti-aging pharmaceutical interventions. Ercc1 Δ/- and Xpg -/- mice show shortened lifespan with accelerated aging across numerous organs and tissues. Previously, we demonstrated that a well-established anti-aging intervention, dietary restriction, reduced DNA damage, and dramatically improved healthspan, strongly extended lifespan, and delayed all aging pathology investigated. Here, we further utilize the short lifespan and early onset of signs of neurological degeneration in Ercc1 Δ/- and Xpg -/- mice to test compounds that influence nutrient sensing (metformin, acarbose, resveratrol), inflammation (aspirin, ibuprofen), mitochondrial processes (idebenone, sodium nitrate, dichloroacetate), glucose homeostasis (trehalose, GlcNAc) and nicotinamide adenine dinucleotide (NAD+) metabolism. While some of the compounds have shown anti-aging features in WT animals, most of them failed to significantly alter lifespan or features of neurodegeneration of our mice. The two NAD+ precursors; nicotinamide riboside (NR) and nicotinic acid (NA), did however induce benefits, consistent with the role of NAD+ in facilitating DNA damage repair. Together, our results illustrate the applicability of short-lived repair mutants for systematic screening of anti-aging interventions capable of reducing DNA damage accumulation.

Pilocapine alters NMDA receptor expression and function in hippocampal neurons: NADPH oxidase and ERK1/2 mechanisms.

The molecular basis for epileptogenesis remains poorly defined, but repeated or prolonged seizures can cause altered hippocampal N-methyl D-aspartate receptor (NMDAR) stoichiometry, loss of hippocampal neurons, and aberrant mossy fiber sprouting. Using the muscarinic receptor 1 (m1R) agonist, pilocarpine (PILO), in hippocampal cell cultures we explored the early sequence of molecular events that occur within 24h of the initial insult and result in altered neuronal function during epileptogenesis. Our findings show that PILO-induced, m1R-mediated, inositol 1,4,5-trisphosphate (IP3) synthesis constitutes an early, crucial biochemical event required for NMDAR hyperactivation and subsequent NADPH oxidase (NOX) activation and NMDAR-independent ERK1/2 phoshorylation. Together, but not separately, NOX activation and ERK1/2 phosphorylation induce alterations in NMDAR stoichiometry through the upregulation of NR1 and NR2B subunits. Lastly, we demonstrated that PILO-mediated oxidative stress alters NMDAR function through the redox modulation of cysteine residues. The in vitro results related to thiol oxidation, NOX activation, ERK1/2 phosphorylation and NMDAR upregulation were confirmed in vivo, 24h after treatment of adult rats with PILO. These results obtained in PILO-treated primary hippocampal neurons--and confirmed in vivo at the same time-point after PILO--provide a better understanding of the early cellular responses during epileptogenesis and identify potential therapeutic targets to prevent development of chronic epilepsy.

The Coming of Age for Big Data in Systems Radiobiology, an Engineering Perspective.

As high-throughput approaches in biological and biomedical research are transforming the life sciences into information-driven disciplines, modern analytics platforms for big data have started to address the needs for efficient and systematic data analysis and interpretation. We observe that radiobiology is following this general trend, with -omics information providing unparalleled depth into the biomolecular mechanisms of radiation response-defined as systems radiobiology. We outline the design of computational frameworks and discuss the analysis of big data in low-dose ionizing radiation (LDIR) responses of the mammalian brain. Following successful examples and best practices of approaches for the analysis of big data in life sciences and health care, we present the needs and requirements for radiation research. Our goal is to raise awareness for the radiobiology community about the new technological possibilities that can capture complex information and execute data analytics on a large scale. The production of large data sets from genome-wide experiments (quantity) and the complexity of radiation research with multidimensional experimental designs (quality) will necessitate the adoption of latest information technologies. The main objective was to translate research results into applied clinical and epidemiological practice and understand the responses of biological tissues to LDIR to define new radiation protection policies. We envisage a future where multidisciplinary teams include data scientists, artificial intelligence experts, DevOps engineers, and of course radiation experts to fulfill the augmented needs of the radiobiology community, accelerate research, and devise new strategies.

Gender biased neuroprotective effect of Transferrin Receptor 2 deletion in multiple models of Parkinson's disease.

Alterations in the metabolism of iron and its accumulation in the substantia nigra pars compacta accompany the pathogenesis of Parkinson's disease (PD). Changes in iron homeostasis also occur during aging, which constitutes a PD major risk factor. As such, mitigation of iron overload via chelation strategies has been considered a plausible disease modifying approach. Iron chelation, however, is imperfect because of general undesired side effects and lack of specificity; more effective approaches would rely on targeting distinctive pathways responsible for iron overload in brain regions relevant to PD and, in particular, the substantia nigra. We have previously demonstrated that the Transferrin/Transferrin Receptor 2 (TfR2) iron import mechanism functions in nigral dopaminergic neurons, is perturbed in PD models and patients, and therefore constitutes a potential therapeutic target to halt iron accumulation. To validate this hypothesis, we generated mice with targeted deletion of TfR2 in dopaminergic neurons. In these animals, we modeled PD with multiple approaches, based either on neurotoxin exposure or alpha-synuclein proteotoxic mechanisms. We found that TfR2 deletion can provide neuroprotection against dopaminergic degeneration, and against PD- and aging-related iron overload. The effects, however, were significantly more pronounced in females rather than in males. Our data indicate that the TfR2 iron import pathway represents an amenable strategy to hamper PD progression. Data also suggest, however, that therapeutic strategies targeting TfR2 should consider a potential sexual dimorphism in neuroprotective response.

Generation, characterization, and drug sensitivities of 12 patient-derived IDH1-mutant glioma cell cultures.

BACKGROUND: Mutations of the isocitrate dehydrogenase (IDH) gene occur in over 80% of low-grade gliomas and secondary glioblastomas. Despite considerable efforts, endogenous in vitro IDH-mutated glioma models remain scarce. Availability of these models is key for the development of new therapeutic interventions. METHODS: Cell cultures were established from fresh tumor material and expanded in serum-free culture media. D-2-Hydroxyglutarate levels were determined by mass spectrometry. Genomic and transcriptomic profiling were carried out on the Illumina Novaseq platform, methylation profiling was performed with the Infinium MethylationEpic BeadChip array. Mitochondrial respiration was measured with the Seahorse XF24 Analyzer. Drug screens were performed with an NIH FDA-approved anti-cancer drug set and two IDH-mutant specific inhibitors. RESULTS: A set of twelve patient-derived IDHmt cell cultures was established. We confirmed high concordance in driver mutations, copy numbers and methylation profiles between the tumors and derived cultures. Homozygous deletion of CDKN2A/B was observed in all cultures. IDH-mutant cultures had lower mitochondrial reserve capacity. IDH-mutant specific inhibitors did not affect cell viability or global gene expression. Screening of 107 FDA-approved anti-cancer drugs identified nine compounds with potent activity against IDHmt gliomas, including three compounds with favorable pharmacokinetic characteristics for CNS penetration: teniposide, omacetaxine mepesuccinate, and marizomib. CONCLUSIONS: Our twelve IDH-mutant cell cultures show high similarity to the parental tissues and offer a unique tool to study the biology and drug sensitivities of high-grade IDHmt gliomas in vitro. Our drug screening studies reveal lack of sensitivity to IDHmt inhibitors, but sensitivity to a set of nine available anti-cancer agents.

PML-controlled responses in severe congenital neutropenia with ELANE-misfolding mutations.

Mutations in ELANE cause severe congenital neutropenia (SCN), but how they affect neutrophil production and contribute to leukemia predisposition is unknown. Neutropenia is alleviated by CSF3 (granulocyte colony-stimulating factor) therapy in most cases, but dose requirements vary between patients. Here, we show that CD34+CD45+ hematopoietic progenitor cells (HPCs) derived from induced pluripotent stem cell lines from patients with SCN that have mutations in ELANE (n = 2) or HAX1 (n = 1) display elevated levels of reactive oxygen species (ROS) relative to normal iPSC-derived HPCs. In patients with ELANE mutations causing misfolding of the neutrophil elastase (NE) protein, HPCs contained elevated numbers of promyelocyte leukemia protein nuclear bodies, a hallmark of acute oxidative stress. This was confirmed in primary bone marrow cells from 3 additional patients with ELANE-mutant SCN. Apart from responding to elevated ROS levels, PML controlled the metabolic state of these ELANE-mutant HPCs as well as the expression of ELANE, suggestive of a feed-forward mechanism of disease development. Both PML deletion and correction of the ELANE mutation restored CSF3 responses of these ELANE-mutant HPCs. These findings suggest that PML plays a crucial role in the disease course of ELANE-SCN characterized by NE misfolding, with potential implications for CSF3 therapy.

A perspective on DNA damage-induced potentiation of the pentose phosphate shunt and reductive stress in chemoresistance.

Metabolic rearrangements and genome instability are two hallmarks of cancer. Recent evidence from our laboratory demonstrates that persistent DNA lesions hampering transcription may cause glucose rerouting through the pentose phosphate shunt and reductive stress. Here, we highlight the relevance of these findings for cancer and chemoresistance development.