p53-induced up-regulation of MnSOD and GPx but not catalase increases oxidative stress and apoptosis

Navigating the redox landscape: reactive oxygen species in regulation of cell cycle

Objectives: To advance our knowledge of disease mechanisms and therapeutic options, understanding cell cycle regulation is critical. Recent research has highlighted the importance of reactive oxygen species (ROS) in cell cycle regulation. Although excessive ROS levels can lead to age-related pathologies, ROS also play an essential role in normal cellular functions. Many cell cycle regulatory proteins are affected by their redox status, but the precise mechanisms and conditions under which ROS promote or inhibit cell proliferation are not fully understood.Methods: This review presents data from the scientific literature and publicly available databases on changes in redox state during the cell cycle and their effects on key regulatory proteins.Results: We identified redox-sensitive targets within the cell cycle machinery and analysed different effects of ROS (type, concentration, duration of exposure) on cell cycle phases. For example, moderate levels of ROS can promote cell proliferation by activating signalling pathways involved in cell cycle progression, whereas excessive ROS levels can induce DNA damage and trigger cell cycle arrest or cell death.Discussion: Our findings encourage future research focused on identifying redox-sensitive targets in the cell cycle machinery, potentially leading to new treatments for diseases with dysregulated cell proliferation.

Effects of red-light irradiation and melatonininjection on the antioxidant capacity and occurrence of apoptosis in abalones (Haliotis discus hannai) subjected to thermal stress

High ocean temperatures caused by global warming induce oxidative stress in aquatic organisms. Melatonin treatment and irradiation using red light-emitting diodes (LEDs) have been reported to reduce oxidative stress in a few aquatic organisms. However, the effects of red LED irradiation and melatonin injection on the antioxidant capacity and degree of apoptosis in abalones, which are nocturnal organisms, have not yet been reported. In this study, we compared the expression levels of antioxidant enzymes, total antioxidant capacity, and the degree of apoptosis in abalones subjected to red LED irradiation and melatonin treatment. The results revealed that at high water temperatures (25 °C), the mRNA expression levels of the superoxide dismutase (SOD) and glutathione peroxidase (GPx) genes and the antioxidant activity of SOD decreased in abalones in the red-LED irradiated and melatonin-treated groups compared with those in abalones in the control group. Although high water temperatures induced DNA damage in the abalone samples, the degree of apoptosis was lower in the red-LED irradiated and melatonin-treated groups than in the control group. Overall, the abalones in the melatonin-treated and red-LED irradiated groups showed reduced oxidative stress and increased antioxidant enzyme levels under thermal stress compared with those in the control group. Therefore, red LED irradiation is a promising alternative to melatonin treatment, which is difficult to administer continuously for a long time, for protecting abalones from oxidative stress.

Targeting the ATM pathway in cancer: Opportunities, challenges and personalized therapeutic strategies

Ataxia telangiectasia mutated (ATM) kinase plays a pivotal role in orchestrating the DNA damage response, maintaining genomic stability, and regulating various cellular processes. This review provides a comprehensive analysis of ATM's structure, activation mechanisms, and various functions in cancer development, progression, and treatment. I discuss ATM's dual nature as both a tumor suppressor and potential promoter of cancer cell survival in certain contexts. The article explores the complex signaling pathways mediated by ATM, its interactions with other DNA repair mechanisms, and its influence on cell cycle checkpoints, apoptosis, and metabolism. I examine the clinical implications of ATM alterations, including their impact on cancer predisposition, prognosis, and treatment response. The review highlights recent advances in ATM-targeted therapies, discussing ongoing clinical trials of ATM inhibitors and their potential in combination with other treatment modalities. I also address the challenges in developing effective biomarkers for ATM activity and patient selection strategies for personalized cancer therapy. Finally, I outline future research directions, emphasizing the need for refined biomarker development, optimized combination therapies, and strategies to overcome potential resistance mechanisms. This comprehensive overview underscores the critical importance of ATM in cancer biology and its emerging potential as a therapeutic target in precision oncology.

Disulfiram/copper complex improves the effectiveness of the WEE1 inhibitor Adavosertib in p53 deficient non-small cell lung cancer via ferroptosis

Cancer cells lacking functional p53 exhibit poor prognosis, necessitating effective treatment strategies. Inhibiting WEE1, the G2/M cell cycle checkpoint gatekeeper, represents a promising approach for treating p53-deficient NSCLC. Here, we investigate the connection between p53 and WEE1, as well as explore a synergistic therapeutic approach for managing p53-deficient NSCLC. Our study reveals that p53 deficiency upregulates both protein levels and kinase activity of WEE1 by inhibiting its SUMOylation process, thereby enhancing the susceptibility of p53-deficient NSCLC to WEE1 inhibitors. Furthermore, we demonstrate that the WEE1 inhibitor Adavosertib induces intracellular lipid peroxidation, specifically in p53-deficient NSCLC cells, suggesting potential synergy with pro-oxidant reagents. Repurposing Disulfiram (DSF), an alcoholism medication used in combination with copper (Cu), exhibits pro-oxidant properties against NSCLC. The levels of WEE1 protein in p53-deficient NSCLC cells treated with DSF-Cu exhibit a time-dependent increase. Subsequent evaluation of the combination therapy involving Adavosertib and DSF-Cu reveals reduced cell viability along with smaller tumor volumes and lighter tumor weights observed in both p53-deficient cells and xenograft models while correlating with solute carrier family 7-member 11 (SLC7A11)/glutathione-regulated ferroptosis pathway activation. In conclusion, our findings elucidate the molecular interplay between p53 and WEE1 and unveil a novel synergistic therapeutic strategy for treating p53-deficient NSCLC.

Melatonin and Metformin Mitigate Doxorubicin-Induced Alveolar Bone Toxicity

Evidence concerning the osteotoxic effects of chemotherapy (doxorubicin) has been previously described. Periodontitis also progressively increases in patients receiving chemotherapy; however, the beneficial effects of melatonin and metformin on the alleviation of doxorubicin-induced osteotoxicity have never been investigated. Therefore, we investigated the negative impact of doxorubicin on alveolar bone homeostasis and the benefits of melatonin and metformin on the attenuation of doxorubicin-induced alveolar bone toxicity. Male Wistar rats were divided into 4 groups to receive either 1 mL of normal saline solution as a control group, 3 mg/kg of doxorubicin, 3 mg/kg of doxorubicin plus 10 mg/kg of melatonin, or 3 mg/kg of doxorubicin plus 250 mg/kg of metformin. Doxorubicin treatment was given on days 0, 4, 8, 15, 22, and 29, while interventions were given daily on days 0 to 29. Following euthanasia, blood and alveolar bones were collected for evaluation of oxidative stress, bone remodeling, inflammation, microarchitecture, and periodontal condition. We found that doxorubicin increased systemic oxidative stress, decreased antioxidative capacity, increased inflammation, decreased bone formation, increased bone reabsorption, impaired microarchitecture, and impaired periodontal condition of the alveolar bone. Although cotreatment with melatonin or metformin resulted in some improvement in these parameters, cotreatment with melatonin was more effective than cotreatment with metformin in terms of decreasing oxidative stress, reducing bone resorption, and improving microarchitecture and periodontal condition. All of these findings highlight the potential for antioxidants, especially melatonin, to ameliorate doxorubicin-induced alveolar bone toxicity.

GPCR-Gα13 Involvement in Mitochondrial Function, Oxidative Stress, and Prostate Cancer

Gα13 and Gα12, encoded by the GNA13 and GNA12 genes, respectively, are members of the G12 family of Gα proteins that, along with their associated Gβγ subunits, mediate signaling from specific G protein-coupled receptors (GPCRs). Advanced prostate cancers have increased expression of GPCRs such as CXC Motif Chemokine Receptor 4 (CXCR4), lysophosphatidic acid receptor (LPAR), and protease activated receptor 1 (PAR-1). These GPCRs signal through either the G12 family, or through Gα13 exclusively, often in addition to other G proteins. The effect of Gα13 can be distinct from that of Gα12, and the role of Gα13 in prostate cancer initiation and progression is largely unexplored. The oncogenic effect of Gα13 on cell migration and invasion in prostate cancer has been characterized, but little is known about other biological processes such as mitochondrial function and oxidative stress. Current knowledge on the link between Gα13 and oxidative stress is based on animal studies in which GPCR-Gα13 signaling decreased superoxide levels, and the overexpression of constitutively active Gα13 promoted antioxidant gene activation. In human samples, mitochondrial superoxide dismutase 2 (SOD2) correlates with prostate cancer risk and prognostic Gleason grade. However, overexpression of SOD2 in prostate cancer cells yielded conflicting results on cell growth and survival under basal versus oxidative stress conditions. Hence, it is necessary to explore the effect of Gα13 on prostate cancer tumorigenesis, as well as the effect of Gα13 on SOD2 in prostate cancer cell growth under oxidative stress conditions.

Therapeutic Applications of Nanoformulated Resveratrol and Quercetin Phytochemicals in Colorectal Cancer-An Updated Review

Natural compounds such as polyphenols play several positive roles in maintaining the oxidative and inflammatory capacity of cells, which leads to their potential use as anticancer therapeutics. There is promising evidence for the in vitro and in vivo anticancer activity of many polyphenols, including resveratrol and quercetin, specifically in the treatment of colorectal cancer (CRC). There is a clear association between resveratrol and quercetin in interfering with the mechanistic pathways involved in CRC, such as Wnt, P13K/AKT, caspase-3, MAPK, NF-κB, etc. These molecular pathways establish the role of resveratrol and quercetin in controlling cancer cell growth, inducing apoptosis, and inhibiting metastasis. The major bottleneck in the progression of the use of resveratrol and quercetin as anticancer therapeutics is their reduced bioavailability in vivo because of their rapid metabolism in humans. Recent advancements in various nanotechnological formulations are promising for overcoming these bioavailability issues. Various nanoformulations of resveratrol and quercetin have shown an optimistic impact on reducing the solubility and improving the stability of resveratrol and quercetin in vivo. A combinatorial approach using nanoformulations of resveratrol with quercetin could potentially increase the impact of resveratrol in controlling CRC cell proliferation. This review discusses the mechanism of resveratrol and quercetin, the two bioactive polyphenolics, in colon cancer, with an emphasis on various types of nanoformulations of the two molecules targeting colon cancer. It also explores the synergistic effect of combining resveratrol and quercetin in various nanoformulations, targeting colon cancer. This research delves into the enhanced pharmacokinetics and potential chemotherapeutic benefits of these bioactive polyphenolics when used together in innovative ways.

Redox signaling in cell fate: Beyond damage

This review explores the nuanced role of reactive oxygen species (ROS) in cell fate, challenging the traditional view that equates ROS with cellular damage. Through significant technological advancements in detecting localized redox states and identifying oxidized cysteines, a paradigm shift has emerged: from ROS as merely damaging agents to crucial players in redox signaling. We delve into the intricacies of redox mechanisms, which, although confined, exert profound influences on cellular physiological responses. Our analysis extends to both the positive and negative impacts of these mechanisms on cell death processes, including uncontrolled and programmed pathways. By unraveling these complex interactions, we argue against the oversimplified notion of a 'stress response', advocating for a more nuanced understanding of redox signaling. This review underscores the importance of localized redox states in determining cell fate, highlighting the sophistication and subtlety of ROS functions beyond mere damage.

The pleiotropic functions of reactive oxygen species in cancer

Cellular redox homeostasis is an essential, dynamic process that ensures the balance between reducing and oxidizing reactions within cells and thus has implications across all areas of biology. Changes in levels of reactive oxygen species can disrupt redox homeostasis, leading to oxidative or reductive stress that contributes to the pathogenesis of many malignancies, including cancer. From transformation and tumor initiation to metastatic dissemination, increasing reactive oxygen species in cancer cells can paradoxically promote or suppress the tumorigenic process, depending on the extent of redox stress, its spatiotemporal characteristics and the tumor microenvironment. Here we review how redox regulation influences tumorigenesis, highlighting therapeutic opportunities enabled by redox-related alterations in cancer cells.

The combination of hypoxia and high temperature affects heat shock, anaerobic metabolism, and pentose phosphate pathway key components responses in the white shrimp (Litopenaeus vannamei)

Due to global warming, world water bodies have higher temperatures and lower oxygen concentrations that affect aquatic species including the white shrimp Litopenaeus vannamei. This species withstands these conditions, but the information of the physiological responses that allow them to survive are scarce. We analyzed the effects of high temperature, hypoxia, reoxygenation, and the combination of these factors on the relative expression of selected genes: HSF1, Hsp70, p53, TIGAR, HIF-1α, and VEGF1-3 in gills of L. vannamei. Additionally, glucose, lactate, NADP, and NADPH were determined. HSF1 was up-regulated in the high temperature and oxygen stress conditions, but Hsp70 was up-regulated only in reoxygenation at both temperatures. HIF-1α was also up-regulated by reoxygenation in both temperatures. Meanwhile, the VEGF genes were not altered by the stress conditions, since none of them changed expression drastically. p53 relative expression remained stable at the tested stress conditions, which prompts to the maintenance of antioxidant defenses. TIGAR expression was induced in normoxia and hypoxia at high temperature, which induced NADPH content helping to scavenge reactive oxygen species (ROS). Additionally, high temperature caused higher glucose and lactate content in normoxia and hypoxia, indicating carbohydrate mobilization and a switch to anaerobic metabolism. The results showed that HSF1, the anaerobic metabolism and the pentose phosphate pathway (PPP) are crucial for the shrimp response to these abiotic stress conditions and contribute to their survival.

Targeting p53 pathways: mechanisms, structures, and advances in therapy

The TP53 tumor suppressor is the most frequently altered gene in human cancers, and has been a major focus of oncology research. The p53 protein is a transcription factor that can activate the expression of multiple target genes and plays critical roles in regulating cell cycle, apoptosis, and genomic stability, and is widely regarded as the "guardian of the genome". Accumulating evidence has shown that p53 also regulates cell metabolism, ferroptosis, tumor microenvironment, autophagy and so on, all of which contribute to tumor suppression. Mutations in TP53 not only impair its tumor suppressor function, but also confer oncogenic properties to p53 mutants. Since p53 is mutated and inactivated in most malignant tumors, it has been a very attractive target for developing new anti-cancer drugs. However, until recently, p53 was considered an "undruggable" target and little progress has been made with p53-targeted therapies. Here, we provide a systematic review of the diverse molecular mechanisms of the p53 signaling pathway and how TP53 mutations impact tumor progression. We also discuss key structural features of the p53 protein and its inactivation by oncogenic mutations. In addition, we review the efforts that have been made in p53-targeted therapies, and discuss the challenges that have been encountered in clinical development.

Plant-derived natural products and combination therapy in liver cancer

Liver cancer is one of the malignant cancers globally and seriously endangers human health because of its high morbidity and mortality. Plant-derived natural products have been evaluated as potential anticancer drugs due to low side effects and high anti-tumor efficacy. However, plant-derived natural products also have defects of poor solubility and cumbersome extraction process. In recent years, a growing numbers of plant derived natural products have been used in combination therapy of liver cancer with conventional chemotherapeutic agents, which has improved clinical efficacy through multiple mechanisms, including inhibition of tumor growth, induction of apoptosis, suppression of angiogenesis, enhancement of immunity, reversal of multiple drug resistance and reduction of side effects. The therapeutic effects and mechanisms of plant-derived natural products and combination therapy on liver cancer are reviewed to provide references for developing anti-liver-cancer strategies with high efficacy and low side effects.

The Normal, the Radiosensitive, and the Ataxic in the Era of Precision Radiotherapy: A Narrative Review

(1) Background: radiotherapy is a cornerstone of cancer treatment. When delivering a tumoricidal dose, the risk of severe late toxicities is usually kept below 5% using dose-volume constraints. However, individual radiation sensitivity (iRS) is responsible (with other technical factors) for unexpected toxicities after exposure to a dose that induces no toxicity in the general population. Diagnosing iRS before radiotherapy could avoid unnecessary toxicities in patients with a grossly normal phenotype. Thus, we reviewed iRS diagnostic data and their impact on decision-making processes and the RT workflow; (2) Methods: following a description of radiation toxicities, we conducted a critical review of the current state of the knowledge on individual determinants of cellular/tissue radiation; (3) Results: tremendous advances in technology now allow minimally-invasive genomic, epigenetic and functional testing and a better understanding of iRS. Ongoing large translational studies implement various tests and enriched NTCP models designed to improve the prediction of toxicities. iRS testing could better support informed radiotherapy decisions for individuals with a normal phenotype who experience unusual toxicities. Ethics of medical decisions with an accurate prediction of personalized radiotherapy's risk/benefits and its health economics impact are at stake; (4) Conclusions: iRS testing represents a critical unmet need to design personalized radiotherapy protocols relying on extended NTCP models integrating iRS.

Inhibition of microRNA-200c preserves astrocyte sirtuin-1 and mitofusin-2, and protects against hippocampal neurodegeneration following global cerebral ischemia in mice

Memory impairment remains a leading disability in survivors of global cerebral ischemia, occurring secondary to delayed neurodegeneration of hippocampal cornu ammonis-1 (CA1) neurons. MicroRNA-200c (miR-200c) is induced following ischemic stress and we have previously demonstrated that pre-treatment with anti-miR-200c is protective against embolic stroke in mice. In the present study we assessed the role of miR-200c on CA1 neurodegeneration, sirtuin-1 (SIRT1), and mitochondrial dynamic protein expression in a mouse model of transient global cerebral ischemia and in vitro in primary mouse astrocyte cultures after simulated ischemia. Mice were subjected to 10 min bilateral common carotid artery occlusion plus hypotension with 5% isoflurane. After 2 h recovery mice were treated with intravenous injection of either anti-miR-200c or mismatch control. Memory function was assessed by Barnes maze at post-injury days 3 and 7. Mice were sacrificed at post-injury day 7 for assessment of brain cell-type specific expression of miR-200c, SIRT1, and the mitochondrial fusion proteins mitofusin-2 (MFN2) and OPA1 via complexed fluorescent in situ hybridization and fluorescent immunohistochemistry. Global cerebral ischemia induced significant loss of CA1 neurons, impaired memory performance and decreased expression of CA1 SIRT1, MFN2, and OPA1. Post-injury treatment with anti-miR-200c significantly improved survival, prevented CA1 neuronal loss, improved post-injury performance in Barnes maze, and was associated with increased post-injury expression of CA1 SIRT1 and MFN2 in astrocytes. In vitro, primary mouse astrocyte cultures pre-treated with miR-200c inhibitor prior to oxygen/glucose deprivation preserved expression of SIRT1 and MFN2, and decreased reactive oxygen species generation, whereas pre-treatment with miR-200c mimic had opposite effects that could be reversed by co-treatment with SIRT1 activator. These results suggest that miR-200c regulates astrocyte mitochondrial homeostasis via targeting SIRT1, and that CA1 astrocyte mitochondria and SIRT1 represent potential post-injury therapeutic targets to preserve cognitive function in survivors of global cerebral ischemia.

The complexity of p53-mediated metabolic regulation in tumor suppression

Although the classic activities of p53 including induction of cell-cycle arrest, senescence, and apoptosis are well accepted as critical barriers to cancer development, accumulating evidence suggests that loss of these classic activities is not sufficient to abrogate the tumor suppression activity of p53. Numerous studies suggest that metabolic regulation contributes to tumor suppression, but the mechanisms by which it does so are not completely understood. Cancer cells rewire cellular metabolism to meet the energetic and substrate demands of tumor development. It is well established that p53 suppresses glycolysis and promotes mitochondrial oxidative phosphorylation through a number of downstream targets against the Warburg effect. The role of p53-mediated metabolic regulation in tumor suppression is complexed by its function to promote both cell survival and cell death under different physiological settings. Indeed, p53 can regulate both pro-oxidant and antioxidant target genes for complete opposite effects. In this review, we will summarize the roles of p53 in the regulation of glucose, lipid, amino acid, nucleotide, iron metabolism, and ROS production. We will highlight the mechanisms underlying p53-mediated ferroptosis, AKT/mTOR signaling as well as autophagy and discuss the complexity of p53-metabolic regulation in tumor development.

Arabic Gum Could Alleviate the Aflatoxin B1-provoked Hepatic Injury in Rat: The Involvement of Oxidative Stress, Inflammatory, and Apoptotic Pathways

Aflatoxin B₁ (AF) is an unavoidable environmental pollutant that contaminates food, feed, and grains, which seriously threatens human and animal health. Arabic gum (AG) has recently evoked much attention owing to its promising therapeutic potential. Thus, the current study was conducted to look into the possible mechanisms beyond the ameliorative activity of AG against AF-inflicted hepatic injury. Male Wistar rats were assigned into four groups: Control, AG (7.5 g/kg b.w/day, orally), AF (200 µg/kg b.w), and AG plus AF group. AF induced marked liver damage expounded by considerable changes in biochemical profile and histological architecture. The oxidative stress stimulated by AF boosted the production of plasma malondialdehyde (MDA) level along with decreases in the total antioxidant capacity (TAC) level and glutathione peroxidase (GPx) activity. Additionally, AF exposure was associated with down-regulation of the nuclear factor erythroid2–related factor2 (Nrf2) and superoxide dismutase1 (SOD1) protein expression in liver tissue. Apoptotic cascade has also been evoked following AF-exposure, as depicted in overexpression of cytochrome c (Cyto c), cleaved Caspase3 (Cl. Casp3), along with enhanced up-regulation of inflammatory mediators such as tumor necrosis factor-α (TNF-α), interleukin (IL)-6, inducible nitric oxide synthase (iNOS), and nuclear factor kappa-B transcription factor/p65 (NF-κB/p65) mRNA expression levels. Interestingly, the antioxidant and anti-inflammatory contents of AG may reverse the induced oxidative damage, inflammation, and apoptosis in AF-exposed animals.

Role of p53 in Regulating Radiation Responses

p53 is known as the guardian of the genome and plays various roles in DNA damage and cancer suppression. The p53 gene was found to express multiple p53 splice variants (isoforms) in a physiological, tissue-dependent manner. The various genes that up- and down-regulated p53 are involved in cell viability, senescence, inflammation, and carcinogenesis. Moreover, p53 affects the radioadaptive response. Given that several studies have already been published on p53, this review presents its role in the response to gamma irradiation by interacting with MDM2, NF-κB, and miRNA, as well as in the inflammation processes, senescence, carcinogenesis, and radiation adaptive responses. Finally, the potential of p53 as a biomarker is discussed.

Administration time-dependent effects of poly (I:C) on antioxidant and immune responses along the diurnal time scale in zebrafish

The circadian clock of vertebrates regulates many biological processes, including the immune system. This paper investigated whether responsiveness to poly (I:C), a synthetic analog of double-stranded RNA used as an immunostimulant, exhibits day/night differences in zebrafish. Fish were intraperitoneally (IP) injected with either phosphate-buffered saline (PBS) or poly (I:C) at two different time points: "Zeitgeber Time" (ZT) 4 (day) and ZT16 (night). Then, 6 h later, fish were euthanized, and tissue samples (skin, liver and kidney) were collected. A control group (intact fish) was also sampled at the same time points. The effect of poly (I:C) on the expression of antioxidant and immune genes was time-of-day-dependent, and the response was stronger following poly (I:C) administration in the day than at night. Time-dependent differences were observed for some genes in the PBS and control groups. However, these differences were tissue-specific. In liver, almost all the genes were affected by time of day. In kidney, poly (I:C) affected the expression of all the gene markers regardless of administration time. These findings highlight the importance of considering the time to administer poly (I:C) when evaluating the fish immune response.

Effect of Acrylamide Treatment on Cyp2e1 Expression and Redox Status in Rat Hepatocytes

Acrylamide (AA) toxicity is associated with oxidative stress. During detoxification, AA is either coupled to gluthatione or biotransformed to glycidamide by the enzyme cytochrome P450 2E1 (CYP2E1). The aim of our study was to examine the hepatotoxicity of AA in vivo and in vitro. Thirty male Wistar rats were treated with 25 or 50 mg/kg b.w. of AA for 3 weeks. Qualitative and quantitative immunohistochemical evaluation of inducible nitric oxide synthase (iNOS), CYP2E1, catalase (CAT), superoxide dismutase 1 (SOD1), and SOD2 expression in liver was carried out. Bearing in mind that the liver is consisted mainly of hepatocytes, in a parallel study, we used the rat hepatoma cell line H4IIE to investigate the effects of AA at IC20 and IC50 concentrations on the redox status and the activity of CAT, SOD, and glutathione-S-transferase (GST), their gene expression, and CYP2E1 and iNOS expression. Immunohistochemically stained liver sections showed that treatment with AA25mg induced a significant decrease of CYP2E1 protein expression (p < 0.05), while treatment with AA50mg led to a significant increase of iNOS protein expression (p < 0.05). AA treatment dose-dependently elevated SOD2 protein expression (p < 0.05), while SOD1 protein expression was significantly increased only at AA50mg (p < 0.05). CAT protein expression was not significantly affected by AA treatments (p > 0.05). In AA-treated H4IIE cells, a concentration-dependent significant increase in lipid peroxidation and nitrite levels was observed (p < 0.05), while GSH content and SOD activity significantly decreased in a concentration-dependent manner (p < 0.05). AA IC50 significantly enhanced GST activity (p < 0.05). The level of mRNA significantly increased in a concentration-dependent manner for iNOS, SOD2, and CAT in AA-treated H4IIE cells (p < 0.05). AA IC50 significantly increased the transcription of SOD1, GSTA2, and GSTP1 genes (p < 0.05), while AA IC20 significantly decreased mRNA for CYP2E1 in H4IIE cells (p < 0.05). Obtained results indicate that AA treatments, both in vivo and in vitro, change hepatocytes; drug-metabolizing potential and disturb its redox status.

Glutathione Peroxidase GPX1 and Its Dichotomous Roles in Cancer

As the first identified selenoprotein, glutathione peroxidase 1 (GPX1) is a widely and abundantly expressed antioxidant enzyme. GPX1 utilizes glutathione as a substrate to catalyze hydrogen peroxide, lipid peroxide, and peroxynitrite, thereby reducing intracellular oxidative stress. The GPX1 gene is regulated at transcriptional, post-transcriptional, and translational levels. Numerous case-control studies and meta-analyses have assessed the association between a functional genetic polymorphism of the GPX1 gene, named Pro198Leu (rs1050450 C>T), and cancer susceptibility in different populations. GPX1 polymorphism has type-specific effects as a candidate marker for cancer risk, but the association between GPX1 variants and cancer susceptibility remains controversial in different studies. GPX1 is abnormally elevated in most types of cancer but has complex dichotomous roles as tumor suppressor and promoter in different cancers. GPX1 can participate in various signaling pathways to regulate tumor biological behaviors, including cell proliferation, apoptosis, invasion, immune response, and chemoresistance. In this review, we comprehensively summarize the controversial associations between GPX1 polymorphism and cancer risks and further discuss the relationships between the aberrant expressions of GPX1 and tumorigenesis. Further studies are needed to elucidate the clinical significance of GPX1 as a potential prognostic biomarker and novel therapeutic target in various malignancies.

Application of Quercetin in the Treatment of Gastrointestinal Cancers

Many cellular signaling pathways contribute to the regulation of cell proliferation, division, motility, and apoptosis. Deregulation of these pathways contributes to tumor cell initiation and tumor progression. Lately, significant attention has been focused on the use of natural products as a promising strategy in cancer treatment. Quercetin is a natural flavonol compound widely present in commonly consumed foods. Quercetin has shown significant inhibitory effects on tumor progression via various mechanisms of action. These include stimulating cell cycle arrest or/and apoptosis as well as its antioxidant properties. Herein, we summarize the therapeutic effects of quercetin in gastrointestinal cancers (pancreatic, gastric, colorectal, esophageal, hepatocellular, and oral).

Oxidative Stress and Redox Signaling in the Pathophysiology of Liver Diseases

The increased production of derivatives of molecular oxygen and nitrogen in the form of reactive oxygen species (ROS) and reactive nitrogen species (RNS) lead to molecular damage called oxidative stress. Under normal physiological conditions, the ROS generation is tightly regulated in different cells and cellular compartments. Any disturbance in the balance between the cellular generation of ROS and antioxidant balance leads to oxidative stress. In this article, we discuss the sources of ROS (endogenous and exogenous) and antioxidant mechanisms. We also focus on the pathophysiological significance of oxidative stress in various cell types of the liver. Oxidative stress is implicated in the development and progression of various liver diseases. We narrate the master regulators of ROS-mediated signaling and their contribution to liver diseases. Nonalcoholic fatty liver diseases (NAFLD) are influenced by a "multiple parallel-hit model" in which oxidative stress plays a central role. We highlight the recent findings on the role of oxidative stress in the spectrum of NAFLD, including fibrosis and liver cancer. Finally, we provide a brief overview of oxidative stress biomarkers and their therapeutic applications in various liver-related disorders. Overall, the article sheds light on the significance of oxidative stress in the pathophysiology of the liver. © 2022 American Physiological Society. Compr Physiol 12:3167-3192, 2022.

MDM2 is involved in the regulation of p53 expression in the immune response of oyster Crassostrea hongkongensis

MDM2 (mouse double-minute) and p53 form a negative feedback loop and play a prominent role in preventing the induction of uncontrolled apoptosis. To better understand their potential roles in oyster Crassostrea hongkongensis, MDM2 and p53 homologs were first isolated and cloned in C. hongkongensis (named ChMDM2 and Chp53), and their mRNA expression patterns in tissues and developmental stages were analyzed. Multiple sequence alignment analysis and phylogenetic analysis of ChMDM2 and Chp53 displayed a high degree of homology and conservation. In addition, exposure to Vibrio coralliilyticus resulted in DNA damage and apoptosis in the hemocytes of C. hongkongensis, and found that the mRNA expression level of ChMDM2 was decreased, while the relative expression of Chp53 was significantly increased in the hemocytes and gills. Furthermore, fluorescence from ChMDM2-EGFP and Chp53-Red were found to be distributed in the nucleus of HEK293T cells. Besides, dual-luciferase reporter assays showed that ChMDM2 antagonized with Chp53 and participates in p53 signaling pathway. In addition, the interaction between ChMDM2 and Chp53 was confirmed strongly by Co-immunoprecipitation assays. Furthermore, the results of RNAi showed that ChMDM2 and Chp53 participated in apoptosis which induced infection of V. coralliilyticus. Taken together, our results characterized the features of ChMDM2 and Chp53, which played a critical role in apoptosis of C. hongkongensis.

Targeting prooxidant MnSOD effect inhibits triple-negative breast cancer (TNBC) progression and M2 macrophage functions under the oncogenic stress

Triple-negative breast cancer (TNBC) has been shown with high mitochondrial oxidative phosphorylation and production of reactive oxygen species (ROS). MnSOD (SOD2) is a mitochondrial antioxidant defense that has been implicated in inhibition of human malignancies. However, the impact of MnSOD on immunosuppressive macrophage functions and TNBC aggressiveness has never been explored. We found here that SOD2^high is primarily observed in the aggressive subtypes of HER2(+) breast cancers and TNBCs patients. Further analyses demonstrated that the oncoprotein multiple copies in T-cell malignancy-1 (MCT-1 or MCTS1) induces mitochondrial superoxide dismutase (MnSOD) in TNBC cells by stabilizing the transcription factor Nrf2. SOD2^high/MCTS1^high expression correlates with a poor prognosis in breast cancer patients. MnSOD in TNBC cells functions as a prooxidant peroxidase that increases mitochondrial ROS (mROS) and adaptation to oxidative stress under the oncogenic effect. Interleukin-6 (IL-6) in the MCT-1 pathway elevates Nrf2/MnSOD and mROS levels. Knockdown of MnSOD inhibits TNBC cell invasion, breast cancer stem cells (BCSCs), mROS, and IL-6 excretion promoted by MCT-1. TNBC cells deficient in MnSOD prevent the polarization and chemotaxis of M2 macrophages but improve the ability of M1 macrophages to engulf cancer cells. Quenching mROS with MitoQ, a mitochondria-targeted non-metal-based antioxidant MnSOD mimics, effectively suppresses BCSCs and M2 macrophage invasion exacerbated by MnSOD and MCT-1. Consistently, silencing MnSOD impedes TNBC progression and intratumoral M2 macrophage infiltration. We revealed a novel stratagem for TNBC management involving targeting the MCT-1 oncogene-induced mitochondrial prooxidant MnSOD pathway, which prevents the development of an immunosuppressive tumor microenvironment.

Protein of a thousand faces: The tumor-suppressive and oncogenic responses of p53

The p53 protein is a pleiotropic regulator working as a tumor suppressor and as an oncogene. Depending on the cellular insult and the mutational status, p53 may trigger opposing activities such as cell death or survival, senescence and cell cycle arrest or proliferative signals, antioxidant or prooxidant activation, glycolysis, or oxidative phosphorylation, among others. By augmenting or repressing specific target genes or directly interacting with cellular partners, p53 accomplishes a particular set of activities. The mechanism in which p53 is activated depends on increased stability through post-translational modifications (PTMs) and the formation of higher-order structures (HOS). The intricate cell death and metabolic p53 response are reviewed in light of gaining stability via PTM and HOS formation in health and disease.

Redox Sensitive Cysteine Residues as Crucial Regulators of Wild-Type and Mutant p53 Isoforms

The wild-type protein p53 plays a key role in preventing the formation of neoplasms by controlling cell growth. However, in more than a half of all cancers, the TP53 gene has missense mutations that appear during tumorigenesis. In most cases, the mutated gene encodes a full-length protein with the substitution of a single amino acid, resulting in structural and functional changes and acquiring an oncogenic role. This dual role of the wild-type protein and the mutated isoforms is also evident in the regulation of the redox state of the cell, with antioxidant and prooxidant functions, respectively. In this review, we introduce a new concept of the p53 protein by discussing its sensitivity to the cellular redox state. In particular, we focus on the discussion of structural and functional changes following post-translational modifications of redox-sensitive cysteine residues, which are also responsible for interacting with zinc ions for proper structural folding. We will also discuss therapeutic opportunities using small molecules targeting cysteines capable of modifying the structure and function of the p53 mutant isoforms in view of possible anticancer therapies for patients possessing the mutation in the TP53 gene.

Characterization of p53 From the Marine Crab Portunus trituberculatus and Its Functions Under Low Salinity Conditions

Portunus trituberculatus, or the swimming crab, is tolerant of reduced salinity; however, the molecular mechanism of this tolerance is not clear. Cells can be damaged by hyperosmotic salinity. The protein p53, sometimes referred to as “the guardian of the genome,” displays versatile and important functions under changing environmental conditions. Herein, the P. trituberculatus p53 gene (designated as Ptp53) was cloned and studied. The full-length Ptp53 cDNA comprised 1,544bp, with a 1,314bp open reading frame, which encodes a putative polypeptide of 437 amino acids. Quantitative real-time reverse transcription PCR assays revealed ubiquitous expression of Ptp53 in all tissues examined, with the gills showing the highest expression level. Extensive apoptosis was detected under low salinity conditions using terminal deoxynucleotidyl transferase nick-end-labeling staining. Oxidative stress was induced under low salinity conditions, consequently leading to apoptosis. Low salinity stress caused significant upregulation of Ptp53 mRNA and protein levels in the gills. Moreover, compared with that in the control group, the mortality of Ptp53-silenced crabs under low salinity stress was enhanced significantly. Taken together, our findings suggest that Ptp53, via regulation of apoptosis and antioxidant defense, played important functions in the low salinity stress response of the swimming crab.

Accumulation of cholesterol, triglycerides and ceramides in hepatocellular carcinomas of diethylnitrosamine injected mice

BACKGROUND

Dysregulated lipid metabolism is critically involved in the development of hepatocellular carcinoma (HCC). The respective metabolic pathways affected in HCC can be identified using suitable experimental models. Mice injected with diethylnitrosamine (DEN) and fed a normal chow develop HCC. For the analysis of the pathophysiology of HCC in this model a comprehensive lipidomic analysis was performed.

METHODS

Lipids were measured in tumor and non-tumorous tissues by direct flow injection analysis. Proteins with a role in lipid metabolism were analysed by immunoblot. Mann-Whitney U-test or paired Student´s t-test were used for data analysis.

RESULTS

Intra-tumor lipid deposition is a characteristic of HCCs, and di- and triglycerides accumulated in the tumor tissues of the mice. Peroxisome proliferator-activated receptor gamma coactivator 1 alpha, lipoprotein lipase and hepatic lipase protein were low in the tumors whereas proteins involved in de novo lipogenesis were not changed. Higher rates of de novo lipogenesis cause a shift towards saturated acyl chains, which did not occur in the murine HCC model. Besides, LDL-receptor protein and cholesteryl ester levels were higher in the murine HCC tissues. Ceramides are cytotoxic lipids and are low in human HCCs. Notably, ceramide levels increased in the murine tumors, and the simultaneous decline of sphingomyelins suggests that sphingomyelinases were involved herein. DEN is well described to induce the tumor suppressor protein p53 in the liver, and p53 was additionally upregulated in the tumors.

CONCLUSIONS

Ceramides mediate the anti-cancer effects of different chemotherapeutic drugs and restoration of ceramide levels was effective against HCC. High ceramide levels in the tumors makes the DEN injected mice an unsuitable model to study therapies targeting ceramide metabolism. This model is useful for investigating how tumors evade the cytotoxic effects of ceramides.

Acetate Promotes a Differential Energy Metabolic Response in Human HCT 116 and COLO 205 Colon Cancer Cells Impacting Cancer Cell Growth and Invasiveness

Under dysbiosis, a gut metabolic disorder, short-chain carboxylic acids (SCCAs) are secreted to the lumen, affecting colorectal cancer (CRC) development. Butyrate and propionate act as CRC growth inhibitors, but they might also serve as carbon source. In turn, the roles of acetate as metabolic fuel and protein acetylation promoter have not been clearly elucidated. To assess whether acetate favors CRC growth through active mitochondrial catabolism, a systematic study evaluating acetate thiokinase (AcK), energy metabolism, cell proliferation, and invasiveness was performed in two CRC cell lines incubated with physiological SCCAs concentrations. In COLO 205, acetate (+glucose) increased the cell density (50%), mitochondrial protein content (3–10 times), 2-OGDH acetylation, and oxidative phosphorylation (OxPhos) flux (36%), whereas glycolysis remained unchanged vs. glucose-cultured cells; the acetate-induced OxPhos activation correlated with a high AcK activity, content, and acetylation (1.5–6-fold). In contrast, acetate showed no effect on HCT116 cell growth, OxPhos, AcK activity, protein content, and acetylation. However, a substantial increment in the HIF-1α content, HIF-1α-glycolytic protein targets (1–2.3 times), and glycolytic flux (64%) was observed. Butyrate and propionate decreased the growth of both CRC cells by impairing OxPhos flux through mitophagy and mitochondrial fragmentation activation. It is described, for the first time, the role of acetate as metabolic fuel for ATP supply in CRC COLO 205 cells to sustain proliferation, aside from its well-known role as protein epigenetic regulator. The level of AcK determined in COLO 205 cells was similar to that found in human CRC biopsies, showing its potential role as metabolic marker.

Quercetin as a Novel Therapeutic Approach for Lymphoma

Lymphoma is a name for malignant diseases of the lymphatic system including Hodgkin's lymphoma and non-Hodgkin's lymphoma. Although several approaches are used for the treatment of these diseases, some of them are not successful and have serious adverse effects. Therefore, other effective treatment methods might be interesting. Studies have indicated that plant ingredients play a key role in treating several diseases. Some plants have already shown a potential therapeutic effect on many malignant diseases. Quercetin is a flavonoid found in different plants and could be useful in the treatment of different malignant diseases. Quercetin has its antimalignant effects through targeting main survival pathways activated in tumor cells. In vitro/in vivo experimental studies have demonstrated that quercetin possesses a cytotoxic effect on lymphoid cancer cells. Regardless of the optimum results that have been obtained from both in vitro/in vivo studies, few clinical studies have analyzed the antitumor effects of quercetin in lymphoid cancers. Thus, it seems that more clinical studies should introduce quercetin as a therapeutic, alone or in combination with other chemotherapy agents. Here, in this study, we reviewed the anticancer effects of quercetin and highlighted the potential therapeutic effects of quercetin in various types of lymphoma.

The role of tumor suppressor protein p53 in the mud crab (Scylla paramamosain) after Vibrio parahaemolyticus infection

The tumor suppressor protein p53 plays important roles in DNA repair, cell cycle and genetic stability. In the present study, a p53 gene in the mud crab (Scylla paramamosain) (designated as Sp-53) was identified and characterized. The open reading frame of Sp-53 was comprised a 1383 bp, which encoded a putative protein of 460 amino acids. Sp-53 is expressed in all examined tissues, with the highest expression in hepatopancreas and hemocytes. Vibrio parahaemolyticus infection induced oxidative stress, and led to DNA damage. The Sp-53 transcriptions in hepatopancreas were significantly up-regulated after V. parahaemolyticus infection. RNA interference (RNAi) experiment was used to understand the roles of Sp-53 in response to V. parahaemolyticus infection. Knocking down Sp-53 in vivo significantly reduced the expression of the Mn-SOD, Gpx3 and caspase 3 after V. parahaemolyticus infection. Moreover, the mortality of mud crabs and DNA damage in Sp-53-silenced mud crab challenged with V. parahaemolyticus were significantly higher than those in the control group. All these results suggested that Sp-53 played an important role in responses to V. parahaemolyticus infection through its participation in regulation of antioxidant defense, DNA repair and apoptosis.

Sirtuins and Renal Oxidative Stress

Renal failure is a major health problem that is increasing worldwide. To improve clinical outcomes, we need to understand the basic mechanisms of kidney disease. Aging is a risk factor for the development and progression of kidney disease. Cells develop an imbalance of oxidants and antioxidants as they age, resulting in oxidative stress and the development of kidney damage. Calorie restriction (CR) is recognized as a dietary approach that promotes longevity, reduces oxidative stress, and delays the onset of age-related diseases. Sirtuins, a type of nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase, are considered to be anti-aging molecules, and CR induces their expression. The sirtuin family consists of seven enzymes (Sirt1–7) that are involved in processes and functions related to antioxidant and oxidative stress, such as DNA damage repair and metabolism through histone and protein deacetylation. In fact, a role for sirtuins in the regulation of antioxidants and redox substances has been suggested. Therefore, the activation of sirtuins in the kidney may represent a novel therapeutic strategy to enhancing resistance to many causative factors in kidney disease through the reduction of oxidative stress. In this review, we discuss the relationship between sirtuins and oxidative stress in renal disease.

Calvatia Lilacina Extracts Exert Anti-Breast-Cancer Bioactivity through the Apoptosis Induction Dependent on Mitochondrial Reactive Oxygen Species and Caspase Activation

Puffballs are a class of fungi widely distributed worldwide and associated with various bioactivities. This research mainly showed the antitumor bioactivity of extracts from Calvatia lilacina (CL), which is a common variety of puffballs. NMR and high-performance liquid chromatography methods are used to characterize the extracts. Results showed that CL extracts obtained with petroleum ether, ethyl acetate, ethanol, and water elicited obvious inhibitory effects on the proliferation of A549, Caco-2, and MDA-MB-231. Among these extracts, petroleum ether extract demonstrated the highest performance. This extract was then separated into seven sub-fractions (SFs). Three of these SFs (3#, 6#, and 7#) induces a decrease in the viability of MDA-MB-231 cells in which 7# SF exhibited the highest cytotoxicity, where the major component was found to be ergosta-7,22-dien-3-one. Further tests revealed that 7# SF from petroleum ether extract could trigger severe cell death in human breast cancer cells (MDA-MB-231) by activating the apoptotic pathway dependent on mitochondrial reactive oxygen species and caspase activation. All these results in combination indicate that the mechanism of extract-potentiated apoptosis associates closely with ROS-dependent mitochondrial dysfunction events which further induces mitochondria-mediated intrinsic cytochrome C-caspase-related pathway of apoptosis.Supplemental data for this article is available online at https://doi.org/10.1080/01635581.2021.1936576.

Suggested role of silent information regulator 1 (SIRT1) gene in female infertility: A cross-sectional study in Pakistan

AIM & OBJECTIVE

Silent information regulator 1 (SIRT1) gene stimulates the expression of antioxidants and repairs damaged cells. It affects the mitochondrial activity within the oocytes to overcome the oxidant stress. We aimed to assess an association of SIRT1 polymorphism (Tag SNPs rs10509291 and rs12778366) with fertility, and assess serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), oestradiol, progesterone, manganese superoxide (MnSOD) and SIRT1.

MATERIAL AND METHODS

In this cross-sectional study, 207 fertile and 135 infertile subjects between the ages of 18-45 years were recruited. Polymerase chain reaction (PCR) was performed; products were electrophoresed in a 2% agarose gel. Descriptive analysis of continuous variables was expressed as mean ± standard deviation. Mann-Whitney test was performed for comparison of groups, P value <.001 was considered significant. Single Nucleotide Polymorphism (SNP) data were analysed by applying chi-squared statistics.

RESULTS

All subjects were age matched (P = .896). SIRT1 levels were significantly lower in infertile females when compared with fertile subjects (P < .001). AA (rs10509291) and CC (rs12778366) variant frequency was higher in the infertile than fertile subjects (P < .01). Similarly, the frequency of A allele (rs10509291) and C allele (rs12778366) was higher in infertile subjects (P < .001). Infertile females (29%) showed existence of SNP rs10509291 while 49% demonstrated genetic variation of rs12778366. MnSOD and SIRT1 levels were found to be lower in these subjects.

CONCLUSION

The presence of SIRT1 genetic variants (rs10509291 and rs12778366) apparently disturbs the expression of SIRT1 deteriorating mitochondrial antioxidant function within the oocytes, instigating oxidative stress within. Their probable effect on modulating oocyte maturation may be the cause of infertility in females.

Targeting Neuroinflammation in Brain Cancer: Uncovering Mechanisms, Pharmacological Targets, and Neuropharmaceutical Developments

Gliomas are one of the most lethal types of cancers accounting for ∼80% of all central nervous system (CNS) primary malignancies. Among gliomas, glioblastomas (GBM) are the most aggressive, characterized by a median patient survival of fewer than 15  months. Recent molecular characterization studies uncovered the genetic signatures and methylation status of gliomas and correlate these with clinical prognosis. The most relevant molecular characteristics for the new glioma classification are IDH mutation, chromosome 1p/19q deletion, histone mutations, and other genetic parameters such as ATRX loss, TP53, and TERT mutations, as well as DNA methylation levels. Similar to other solid tumors, glioma progression is impacted by the complex interactions between the tumor cells and immune cells within the tumor microenvironment. The immune system’s response to cancer can impact the glioma’s survival, proliferation, and invasiveness. Salient characteristics of gliomas include enhanced vascularization, stimulation of a hypoxic tumor microenvironment, increased oxidative stress, and an immune suppressive milieu. These processes promote the neuro-inflammatory tumor microenvironment which can lead to the loss of blood-brain barrier (BBB) integrity. The consequences of a compromised BBB are deleteriously exposing the brain to potentially harmful concentrations of substances from the peripheral circulation, adversely affecting neuronal signaling, and abnormal immune cell infiltration; all of which can lead to disruption of brain homeostasis. In this review, we first describe the unique features of inflammation in CNS tumors. We then discuss the mechanisms of tumor-initiating neuro-inflammatory microenvironment and its impact on tumor invasion and progression. Finally, we also discuss potential pharmacological interventions that can be used to target neuro-inflammation in gliomas.

Novel function of PERP-428 variants impacts lung cancer risk through the differential regulation of PTEN/MDM2/p53-mediated antioxidant activity

Lung cancer is the leading cause of cancer-related deaths worldwide. Identifying genetic risk factors and understanding their mechanisms will help reduce lung cancer incidence. The p53 apoptosis effect is related to PMP-22 (PERP), a tetraspan membrane protein, and an apoptotic effector protein downstream of p53. Although historically considered a tumor suppressor, PERP is highly expressed in lung cancers. Stable knockdown of PERP expression induces CL1-5 and A549 lung cancer cell death, but transient knockdown has no effect. Interestingly, relative to the PERP-428GG genotype, PERP-428CC was associated with the highest lung cancer risk (OR = 5.38; 95% CI = 2.12-13.65, p < 0.001), followed by the PERP-428CG genotype (OR = 2.34; 95% CI = 1.55-3.55, p < 0.001). Ectopic expression of PERP-428G, but not PERP-428C, protects lung cancer cells against ROS-induced DNA damage. Mechanistically, PERP-428 SNPs differentially regulate p53 protein stability. p53 negatively regulates the expression of the antioxidant enzymes catalase (CAT) and glutathione reductase (GR), thereby modulating redox status. p53 protein stability is higher in PERP-428C-expressing cells than in PERP-428G-expressing cells because MDM2 expression is decreased and p53 Ser20 phosphorylation is enhanced in PERP-428C-expressing cells. The MDM2 mRNA level is decreased in PERP-428C-expressing cells via PTEN-mediated downregulation of the MDM2 constitutive p1 promoter. This study reveals that in individuals with PERP-428CC, CAT/GR expression is decreased via the PTEN/MDM2/p53 pathway. These individuals have an increased lung cancer risk. Preventive antioxidants and avoidance of ROS stressors are recommended to prevent lung cancer or other ROS-related chronic diseases.

Possible Beneficial Effects of N-Acetylcysteine for Treatment of Triple-Negative Breast Cancer

N-acetylcysteine (NAC) is a widely used antioxidant with therapeutic potential. However, the cancer-promoting effect of NAC observed in some preclinical studies has raised concerns regarding its clinical use. Reactive oxygen species (ROS) can mediate signaling that results in both cancer-promoting and cancer-suppressing effects. The beneficial effect of NAC may depend on whether the type of cancer relies on ROS signaling for its survival and metastasis. Triple-negative breast cancer (TNBC) has aggressive phenotypes and is currently treated with standard chemotherapy as the main systemic treatment option. Particularly, basal-like TNBC cells characterized by inactivated BRCA1 and mutated TP53 produce high ROS levels and rely on ROS signaling for their survival and malignant progression. In addition, the high ROS levels in TNBC cells can mediate the interplay between cancer cells and the tissue microenvironment (TME) to trigger the recruitment and conversion of stromal cells and induce hypoxic responses, thus leading to the creation of cancer-supportive TMEs and increased cancer aggressiveness. However, NAC treatment effectively reduces the ROS production and ROS-mediated signaling that contribute to cell survival, metastasis, and drug resistance in TNBC cells. Therefore, the inclusion of NAC in standard chemotherapy could probably provide additional benefits for TNBC patients.

Olaquindox-Induced Liver Damage Involved the Crosstalk of Oxidative Stress and p53 In Vivo and In Vitro

Olaquindox (OLA), a member of the quinoxaline-N,N-dioxide family, has been widely used as a growth-promoting feed additive and treatment for bacterial infections. The toxicity has been a major concern, and the precise molecular mechanism remains poorly understood. The present study was aimed at investigating the roles of oxidative stress and p53 in OLA-caused liver damage. In a mouse model, OLA administration could markedly cause liver injury as well as the induction of oxidative stress and activation of p53. Antioxidant N-acetylcysteine (NAC) inhibited OLA-induced oxidative stress and p53 activation in vivo. Furthermore, knockout of the p53 gene could significantly inhibit OLA-induced liver damage by inhibiting oxidative stress and the mitochondria apoptotic pathway, compared to the p53 wild-type liver tissue. The cell model in vitro further demonstrated that p53 knockout or knockdown in the HCT116 cell and L02 cell significantly inhibited cell apoptosis and increased cell viability, presented by suppressing ROS production, oxidative stress, and the Nrf2/HO-1 pathway. Moreover, loss of p53 decreased OLA-induced mitochondrial dysfunction and caspase activations, with the evidence of inhibited activation of phosphorylation- (p-) p38 and p-JNK and upregulated cell autophagy via activation of the LC3 and Beclin1 pathway in HCT116 and L02 cells. Taken together, our findings provided a support that p53 primarily played a proapoptotic role in OLA-induced liver damage against oxidative stress and mitochondrial dysfunction, which were largely dependent on suppression of the JNK/p38 pathway and upregulation of the autophagy pathway via activation of LC3 and Beclin1.

Redox Potential of Antioxidants in Cancer Progression and Prevention

The benevolent and detrimental effects of antioxidants are much debated in clinical trials and cancer research. Several antioxidant enzymes and molecules are overexpressed in oxidative stress conditions that can damage cellular proteins, lipids, and DNA. Natural antioxidants remove excess free radical intermediates by reducing hydrogen donors or quenching singlet oxygen and delaying oxidative reactions in actively growing cancer cells. These reducing agents have the potential to hinder cancer progression only when administered at the right proportions along with chemo-/radiotherapies. Antioxidants and enzymes affect signal transduction and energy metabolism pathways for the maintenance of cellular redox status. A decline in antioxidant capacity arising from genetic mutations may increase the mitochondrial flux of free radicals resulting in misfiring of cellular signalling pathways. Often, a metabolic reprogramming arising from these mutations in metabolic enzymes leads to the overproduction of so called ’oncometabolites’ in a state of ‘pseudohypoxia’. This can inactivate several of the intracellular molecules involved in epigenetic and redox regulations, thereby increasing oxidative stress giving rise to growth advantages for cancerous cells. Undeniably, these are cell-type and Reactive Oxygen Species (ROS) specific, which is manifested as changes in the enzyme activation, differences in gene expression, cellular functions as well as cell death mechanisms. Photodynamic therapy (PDT) using light-activated photosensitizing molecules that can regulate cellular redox balance in accordance with the changes in endogenous ROS production is a solution for many of these challenges in cancer therapy.

Targeting ferroptosis in breast cancer

Ferroptosis is a recently discovered distinct type of regulated cell death caused by the accumulation of lipid-based ROS. Metabolism and expression of specific genes affect the occurrence of ferroptosis, making it a promising therapeutic target to manage cancer. Here, we describe the current status of ferroptosis studies in breast cancer and trace the key regulators of ferroptosis back to previous studies. We also compare ferroptosis to common regulated cell death patterns and discuss the sensitivity to ferroptosis in different subtypes of breast cancer. We propose that viewing ferroptosis-related studies from a historical angle will accelerate the development of ferroptosis-based biomarkers and therapeutic strategies in breast cancer.

p53-dependent glutamine usage determines susceptibility to oxidative stress in radioresistant head and neck cancer cells

The manner in which p53 maintains redox homeostasis and the means by which two key metabolic elements, glucose and glutamine, contribute to p53-dependent redox stability remain unclear. To elucidate the manner in which p53 deals with glucose-deprived, reactive oxygen species (ROS)-prone conditions in this regard, two isogenic cancer subclones (HN3R-A and HN3R-B) bearing distinct p53 mutations as an in vitro model of intratumoral p53 heterogeneity were identified. Following cumulative irradiation, the subclones showed a similar metabolic shift to aerobic glycolysis and increasing NADPH biogenesis for cellular defense against oxidative damage irrespective of p53 status. The radioresistant cancer cells became more sensitive to glycolysis-targeting drugs. However, in glucose-deprived and ROS-prone conditions, HN3R-B, the subclone with the original p53 increased the utilization of glutamine by GLS2, thereby maintaining redox homeostasis and ATP. Conversely, HN3R-A, the p53-deficient radioresistant subclone displayed an impairment in glutamine usage and high susceptibility to metabolic stresses as well as ROS-inducing agents despite the increased ROS scavenging system. Collectively, our findings suggest that p53 governs the alternative utilization of metabolic ingredients, such as glucose and glutamine, in ROS-prone conditions. Thus, p53 status may be an important biomarker for selecting cancer treatment strategies, including metabolic drugs and ROS-inducing agents, for recurrent cancers after radiotherapy.

Reactive Oxygen Species Induced p53 Activation: DNA Damage, Redox Signaling, or Both?

Significance: The p53 tumor suppressor has been dubbed the "guardian of genome" because of its various roles in the response to DNA damage such as DNA damage repair, cell cycle arrest, senescence, and apoptosis, all of which are in place to prevent mutations from being passed on down the lineage. Recent Advances: Reactive oxygen species (ROS), for instance hydrogen peroxide derived from mitochondrial respiration, have long been regarded mainly as a major source of cellular damage to DNA and other macromolecules. Critical Issues: More recently, ROS have been shown to also play important physiological roles as second messengers in so-called redox signaling. It is, therefore, not clear whether the observed activation of p53 by ROS is mediated through the DNA damage response, redox signaling, or both. In this review, we will discuss the similarities and differences between p53 activation in response to DNA damage and redox signaling in terms of upstream signaling and downstream transcriptional program activation. Future Directions: Understanding whether and how DNA damage and redox signaling-dependent p53 activation can be dissected could be useful to develop anti-cancer therapeutic p53-reactivation strategies that do not depend on the induction of DNA damage and the resulting additional mutational load.

Copper interferes with selenoprotein synthesis and activity

Selenium and copper are essential trace elements for humans, needed for the biosynthesis of enzymes contributing to redox homeostasis and redox-dependent signaling pathways. Selenium is incorporated as selenocysteine into the active site of redox-relevant selenoproteins including glutathione peroxidases (GPX) and thioredoxin reductases (TXNRD). Copper-dependent enzymes mediate electron transfer and other redox reactions. As selenoprotein expression can be modulated e.g. by H2O2, we tested the hypothesis that copper status affects selenoprotein expression. To this end, hepatocarcinoma HepG2 cells and mice were exposed to a variable copper and selenium supply in a physiologically relevant concentration range, and transcript and protein expression as well as GPX and TXNRD activities were compared. Copper suppressed selenoprotein mRNA levels of GPX1 and SELENOW, downregulated GPX and TXNRD activities and decreased UGA recoding efficiency in reporter cells. The interfering effects were successfully suppressed by applying the copper chelators bathocuproinedisulfonic acid or tetrathiomolybdate. In mice, a decreased copper supply moderately decreased the copper status and negatively affected hepatic TXNRD activity. We conclude that there is a hitherto unknown interrelationship between copper and selenium status, and that copper negatively affects selenoprotein expression and activity most probably via limiting UGA recoding. This interference may be of physiological relevance during aging, where a particular shift in the selenium to copper ratio has been reported. An increased concentration of copper in face of a downregulated selenoprotein expression may synergize and negatively affect the cellular redox homeostasis contributing to disease processes.

Regulatory Phenomena in the Glutathione Peroxidase Superfamily

Significance: The selenium-containing Glutathione peroxidases (GPxs)1-4 protect against oxidative challenge, inhibit inflammation and oxidant-induced regulated cell death. Recent Advances: GPx1 and GPx4 dampen phosphorylation cascades predominantly via prevention of inactivation of phosphatases by H₂O₂ or lipid hydroperoxides. GPx2 regulates the balance between regeneration and apoptotic cell shedding in the intestine. It inhibits inflammation-induced carcinogenesis in the gut but promotes growth of established cancers. GPx3 deficiency facilitates platelet aggregation likely via disinhibition of thromboxane biosynthesis. It is also considered a tumor suppressor. GPx4 is expressed in three different forms. The cytosolic form proved to inhibit interleukin-1-driven nuclear factor κB activation and leukotriene biosynthesis. Moreover, it is a key regulator of ferroptosis, because it reduces hydroperoxy groups of complex lipids and silences lipoxygenases. By alternate substrate use, the nuclear form contributes to chromatin compaction. Mitochondrial GPx4 forms the mitochondrial sheath of spermatozoa and, thus, guarantees male fertility. Out of the less characterized GPxs, the cysteine-containing GPx7 and GPx8 are unique in contributing to oxidative protein folding in the endoplasmic reticulum by reacting with protein isomerase as an alternate substrate. A yeast 2-Cysteine glutathione peroxidase equipped with CP and CR was reported to sense H₂O₂ for inducing an adaptive response. Critical Issues: Most of the findings compiled are derived from tissue culture and/or animal studies only. Their impact on human physiology is sometimes questionable. Future Directions: The expression of individual GPxs and GPx-dependent regulatory phenomena are to be further investigated, in particular in respect to human health.

Olive Leaf Polyphenols Attenuate the Clinical Course of Experimental Autoimmune Encephalomyelitis and Provide Neuroprotection by Reducing Oxidative Stress, Regulating Microglia and SIRT1, and Preserving Myelin Integrity

Numerous evidences suggest that plant polyphenols may have therapeutic benefits in regulating oxidative stress and providing neuroprotection in many neurodegenerative diseases, including multiple sclerosis (MS). However, these mechanisms are not yet completely understood. In this study, we investigated the effect of olive leaf polyphenols on oxidative stress through oxidation marker level and activity (TBARS, SOD, and GPX) and their protein expression (SOD1, SOD2, and GPX1), as well as the protein expression of Sirtuin 1 (SIRT1) and microglia markers (Iba-1, CD206, and iNOS) and myelin integrity (proteolipid protein expression) in the brain of rats with induced experimental autoimmune encephalomyelitis (EAE) and subjected to olive leaf therapy. Experiments were performed in male EAE DA rats, which were randomly divided into 2 main groups: EAE groups treated with the therapy of olive leaf (EAE+TOL) and untreated EAE control groups. The EAE treated groups consumed olive leaf tea instead of drinking water (ad libitum) from the beginning to the end of the experiment. In addition, olive leaf extract was injected intraperitoneally (i.p.) for the 10 continuous days and started on the 8^th day after EAE induction. The clinical course was monitored in both groups until the 30^th day after EAE induction. Our results demonstrated that TOL attenuated the clinical course of EAE; reduced the oxidative stress (by decreasing the concentration of MDA); upregulated antioxidant enzymes (SOD1, SOD2, and GPX1), SIRT1 (overall and microglial), and anti-inflammatory M2 microglia; downregulated proinflammatory M1 type; and preserved myelin integrity. These data support the idea that TOL may be an effective therapeutic approach for treating MS and other neurodegenerative diseases.