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The liver kinase B1 (LKB1) gene is a tumor suppressor associated with the hereditary Peutz-Jeghers syndrome and frequently mutated in non-small cell lung cancer and in cervical cancer. Previous studies showed that the LKB1/AMPK axis is involved in regulation of cell death and survival under metabolic stress. By using isogenic pairs of cancer cell lines, we report here that the genetic loss of LKB1 was associated with increased intracellular levels of total choline containing metabolites and, under oxidative stress, it impaired maintenance of glutathione (GSH) levels. This resulted in markedly increased intracellular reactive oxygen species (ROS) levels and sensitivity to ROS-induced cell death. These effects were rescued by re-expression of LKB1 or pre-treatment with the anti-oxidant and GSH replenisher N-acetyl cysteine. This role of LKB1 in response to ROS-inducing agents was largely AMPK-dependent. Finally, we observed that LKB1 defective cells are highly sensitive to cisplatin and γ-irradiation in vitro, suggesting that LKB1 mutated tumors could be targeted by oxidative stress-inducing therapies., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Xeroderma pigmentosum (XP)-A patients are characterized by increased solar skin carcinogenesis and present also neurodegeneration. XPA deficiency is associated with defective nucleotide excision repair (NER) and increased basal levels of oxidatively induced DNA damage. In this study we search for the origin of increased levels of oxidatively generated DNA lesions in XP-A cell genome and then address the question of whether increased oxidative stress might drive genetic instability. We show that XP-A human primary fibroblasts present increased levels and different types of intracellular reactive oxygen species (ROS) as compared to normal fibroblasts, with O₂₋• and H₂O₂ being the major reactive species. Moreover, XP-A cells are characterized by decreased reduced glutathione (GSH)/oxidized glutathione (GSSG) ratios as compared to normal fibroblasts. The significant increase of ROS levels and the alteration of the glutathione redox state following silencing of XPA confirmed the causal relationship between a functional XPA and the control of redox balance. Proton nuclear magnetic resonance (¹H NMR) analysis of the metabolic profile revealed a more glycolytic metabolism and higher ATP levels in XP-A than in normal primary fibroblasts. This perturbation of bioenergetics is associated with different morphology and response of mitochondria to targeted toxicants. In line with cancer susceptibility, XP-A primary fibroblasts showed increased spontaneous micronuclei (MN) frequency, a hallmark of cancer risk. The increased MN frequency was not affected by inhibition of ROS to normal levels by N-acetyl-L-cysteine., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Cockayne syndrome (CS) is a rare hereditary disorder in which infants suffer severe developmental and neurological alterations and early death. Two genes encoding RNA polymerase II cofactors, CSA and CSB, are mutated in this syndrome. CSA and CSB proteins are known to be involved in the transcription-coupled DNA repair pathway but the sensitivity of mutant cells to a number of physical/chemical agents besides UV radiation, such as ionizing radiation, hydrogen peroxide and bioenergetic inhibitors indicate that these proteins play a pivotal role in additional pathways. In this review we will discuss the evidence that implicate CS proteins in the control of oxidative stress response with special emphasis on recent findings that show an altered redox balance and dysfunctional mitochondria in cells derived from patients. Working models of how these new functions might be key to developmental and neurological disease in CS will be discussed., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Cockayne syndrome (CS) is a rare hereditary multisystem disease characterized by neurological and development impairment, and premature aging. Cockayne syndrome cells are hypersensitive to oxidative stress, but the molecular mechanisms involved remain unresolved. Here we provide the first evidence that primary fibroblasts derived from patients with CS-A and CS-B present an altered redox balance with increased steady-state levels of intracellular reactive oxygen species (ROS) and basal and induced DNA oxidative damage, loss of the mitochondrial membrane potential, and a significant decrease in the rate of basal oxidative phosphorylation. The Na/K-ATPase, a relevant target of oxidative stress, is also affected with reduced transcription in CS fibroblasts and normal protein levels restored upon complementation with wild-type genes. High-resolution magnetic resonance spectroscopy revealed a significantly perturbed metabolic profile in CS-A and CS-B primary fibroblasts compared with normal cells in agreement with increased oxidative stress and alterations in cell bioenergetics. The affected processes include oxidative metabolism, glycolysis, choline phospholipid metabolism, and osmoregulation. The alterations in intracellular ROS content, oxidative DNA damage, and metabolic profile were partially rescued by the addition of an antioxidant in the culture medium suggesting that the continuous oxidative stress that characterizes CS cells plays a causative role in the underlying pathophysiology. The changes of oxidative and energy metabolism offer a clue for the clinical features of patients with CS and provide novel tools valuable for both diagnosis and therapy., (© 2012 The Authors. Aging Cell © 2012 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.)

The physiological response to the physical exercise involves a number of changes in the oxidative balance and in the metabolism of some important biological molecules, including nitric oxide (NO) and heat shock proteins (Hsp 70). With the aim to optimise previous laboratory diagnostic panels, we measured the plasma concentration of reactive oxygen metabolites (ROMs), total antioxidant status (TAS), glutathione reductase (GR) activity, and NO and Hsp 70 levels in 44 elite, antioxidant-supplemented and trained soccer players and in 15 sedentary controls. Although no statistically significant difference between athletes and controls was detected in the plasma level of ROMs and TAS, soccer players showed a significantly higher plasma GR activity, NO and Hst 70 levels than those of sedentary controls. These findings suggest that the measuring of relatively novel biomarkers in sport medicine, like GR, NO and Hsp 70, in addition to the well-known and reliable assays (d-ROMs test and TAS) may be useful to a clinician to better assess and evaluate the benefits of training and/or supplementation programs.

Lipophilic compounds contained in tomato can prevent cardiovascular diseases by modulating the atherogenic processes in vascular endothelium mediated by oxidized low-density lipoproteins (LDLs). We investigated the effects of lycopene on the metabolism of platelet-activating factor (PAF) and its much less biologically active acyl analog, acyl-PAF, known to prevent LDL oxidation. Lycopene, or lycopene in association with alpha-tocopherol, or whole tomato lipophilic extracts (containing more than 80% lycopene) were used in experiments in which endothelial cells (ECs) are known to synthesize PAF following H(2)O(2)-induced oxidative stress. The results indicated that in each case H(2)O(2)-stimulated PAF biosynthesis in ECs, which is catalyzed by acetyl-CoA acetyltransferase (AT), appeared strongly inhibited. However, acyl-PAF biosynthesis, which also occurs through the PAF-dependent transacetylase (TA), was significantly increased by lycopene only when it was in association with alpha-tocopherol or with the minor compounds present in the whole lipophilic tomato extract. These findings suggest that alpha-tocopherol or lipophilic compounds present in tomato juice potentiate the effects of lycopene on the modulation of PAF and acyl-PAF biosynthesis in ECs during oxidative stress.

An increased production of oxidative chemical species and/or a decreased efficacy of antioxidant systems can lead to the breakdown of the oxidative balance, thus generating the so-called oxidative stress, which is generally recognized as playing a relevant pathogenic role in early aging and in several inflammatory and/or degenerative diseases including atherosclerosis and hypertension (and their consequences, such as stroke and myocardial infarction), Alzheimer's disease, Parkinson's disease, and cancer. In particular, the currently available scientific evidence indicates that there is a very close relationship between oxidative stress and nutrition. In a vicious circle where genetic factors and abnormal lifestyles favor the onset of oxidative damage, which in turn may decrease the bioavailability of antioxidants and amplify initial lesions, it is not easy to establish whether oxidative chemical species are the cause or the effect of the observed disease. However, one thing seems evident: the identification, by means of reliable analytical tools, of an impairment of the oxidative balance is the right premise for any rational attempt to correct the disequilibrium between oxidative chemical species production and antioxidant systems efficacy and hence to contribute, in a more scientifically solid and not purely empirical manner, to "add life to years and years to life". The aim of this review was to analyze, with reference to the scientific literature, the analytical performance and clinical applications of currently available tests for the routine assessment of the oxidative balance, especially in the field of nutrition. The biochemical technology has given clinicians and nutritionists the opportunity to identify and quantify many markers of oxidative stress, which are currently used with the general purpose of preventing oxidative damage, diagnosing and monitoring oxidative stress and, finally, evaluating the indications and effectiveness of various antioxidant supplementations and therapeutic interventions. [ABSTRACT FROM AUTHOR]