Contribution of NAD(P)H:quinone oxidoreductase 1 to protection against carcinogenesis, and regulation of its gene by the Nrf2 basic-region leucine zipper and the arylhydrocarbon receptor basic helix-loop-helix transcription factors

The role of nuclear factor erythroid 2-related factor 2 (NRF2) in arsenic toxicity

Arsenic, a naturally occurring toxic element, manifests in various chemical forms and is widespread in the environment. Exposure to arsenic is a well-established risk factor for an elevated incidence of various cancers and chronic diseases. The crux of arsenic-mediated toxicity lies in its ability to induce oxidative stress, characterized by an unsettling imbalance between oxidants and antioxidants, accompanied by the rampant generation of reactive oxygen species and free radicals. In response to this oxidative turmoil, cells deploy their defense mechanisms, prominently featuring the redox-sensitive transcription factor known as nuclear factor erythroid 2-related factor 2 (NRF2). NRF2 stands as a primary guardian against the oxidative harm wrought by arsenic. When oxidative stress activates NRF2, it orchestrates a symphony of downstream antioxidant genes, leading to the activation of pivotal antioxidant enzymes like glutathione-S-transferase, heme oxygenase-1, and NAD(P)H: quinone oxidoreductase 1. This comprehensive review embarks on the intricate and diverse ways by which various arsenicals influence the NRF2 antioxidant pathway and its downstream targets, shedding light on their roles in defending against arsenic exposure toxic effects. It offers valuable insights into targeting NRF2 as a strategy for safeguarding against or treating the harmful and carcinogenic consequences of arsenic exposure.

Dimethylmonothioarsinic acid (DMMTAV) induces NQO1 expression through coordinated activation of NRF2 and AHR pathways

Dimethylmonothioarsinic acid (DMMTAV), a potent toxic metabolite of arsenic, exhibits higher cytotoxicity than other arsenicals. This study investigates its influence on NAD(P)H:quinone oxidoreductase (NQO1) regulation in C57BL/6 mice and Hepa-1c1c7 cells. Mice were administered DMMTAV (6 mg/kg, IP) with or without TCDD (15 µg/kg, IP), and hepatic and extrahepatic tissues were analyzed for NQO1 expression. In vitro, Hepa-1c1c7 cells were treated with 0-2 µM DMMTAV in the presence and absence of TCDD (1 nM), and NQO1 levels were assessed over time. Western blot, real-time PCR, and ARE-luciferase assays determined protein and transcriptional regulation. DMMTAV upregulated NQO1 in liver tissues and induced a time-dependent increase in vitro, peaking at 12 h. It enhanced TCDD-induced NQO1 expression and increased nuclear NRF2 and AHR levels, with peak accumulation at two hours. ARE-luciferase activity confirmed transcriptional activation. These findings reveal DMMTAV enhances NQO1 primarily via NRF2/AHR pathway activation, providing insight into cellular responses to thioarsenicals.

A Review of the Effects of Flavonoids on NAD(P)H Quinone Oxidoreductase 1 Expression and Activity

Cancer is a significant cause of death worldwide. It has been suggested that the consumption of flavonoids decreases the risk for cancer by increasing phase II enzymes, such as Nicotinamide Adenine Dinucleotide Phosphate Hydrogen (NAD(P)H) quinone oxidoreductase 1 (NQO1), glutathione S-transferases, and Uridine 5'-diphospho- (UDP)-glucuronosyltransferases that assist in removing carcinogens from the human body. Flavonoids are bioactive compounds found in a variety of dietary sources, including fruits, vegetables, legumes, nuts, and teas. As such, it is important to investigate which flavonoids are involved in the metabolism of carcinogens to help reduce the risk of cancer. Therefore, the objective of this narrative review was to investigate the effects of commonly consumed flavonoids on NQO1 mRNA expression, protein, and activity in human cell and murine models. PubMed was used to search for peer-reviewed journal articles, which demonstrated that selected flavonoids (e.g., quercetin, apigenin, luteolin, genistein, and daidzein) increase NQO1, and therefore, increase the excretion of carcinogens. However, more research is needed regarding the mechanisms by which flavonoids induce NQO1. Furthermore, it is suggested that future efforts focus on providing precise flavonoid recommendations to decrease the risk factors for chronic diseases.

Anticancer Effect of C19-Position Substituted Geldanamycin Derivatives Targeting NRF2-NQO1-activated Esophageal Squamous Cell Carcinoma

In esophageal squamous cell carcinoma, genetic activation of NRF2 increases resistance to chemotherapy and radiotherapy, which results in a significantly worse prognosis for patients. Therefore NRF2-activated cancers create an urgent clinical need to identify new therapeutic options. In this context, we previously identified the geldanamycin family of HSP90 inhibitors, which includes 17DMAG, to be synthetic lethal with NRF2 activity. As the first-generation of geldanamycin-derivative drugs were withdrawn from clinical trials due to hepatotoxicity, we designed second-generation compounds with C19-substituted structures in order to inhibit glutathione conjugation-mediated hepatotoxicity. In this study, using a variety of in vitro and in vivo cancer models, we found that C19-substituted 17DMAG compounds maintain their enhanced toxicity profile and synthetic lethal interaction with NRF2-NQO1-activated cancer cells. Importantly, using a xenograft mouse tumor model, we found that C19-substituted 17DMAG displayed significant anticancer efficacy against NRF2-NQO1-activated cancer cells without causing hepatotoxicity. These results clearly demonstrate the improved clinical potential for this new class of HSP90 inhibitor anticancer drugs, and suggest that patients with NRF2-NQO1-activated esophageal carcinoma may benefit from this novel therapeutic approach.

Arsenic Trioxide (ATOIII) Induces NAD(P)H Quinone Oxidoreductase 1 (NQO1) Expression in Hepatic and Extrahepatic Tissues of C57BL/6 Mice

Arsenic trioxide (ATOIII) has emerged as a potent therapeutic agent for acute promyelocytic leukemia (APL), yet its clinical application is often limited by significant adverse effects. This study investigates the molecular mechanisms underlying ATOIII's impact on cellular detoxification pathways, focusing on the regulation of NAD(P)H/quinone oxidoreductase (NQO1), a crucial enzyme in maintaining cellular homeostasis and cancer prevention. We explored ATOIII's effects on NQO1 expression in C57BL/6 mice and Hepa-1c1c7 cells, both independently and in combination with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a known NQO1 inducer. Our findings revealed that ATOIII significantly increased NQO1 expression in hepatic and extrahepatic tissues, as well as in Hepa-1c1c7 cells, at mRNA, protein, and activity levels. This upregulation occurred both in the presence and absence of TCDD. Mechanistically, we demonstrated that ATOIII promotes the nuclear translocation of both nuclear factor erythroid 2-related factor-2 (NRF2) and aryl hydrocarbon receptor (AHR) transcription factors. Furthermore, ATOIII exposure increased antioxidant response element (ARE)-driven reporter gene activity, indicating a transcriptional mechanism of NQO1 induction. Notably, gene silencing experiments confirmed the critical roles of both NRF2 and AHR in mediating ATOIII-induced NQO1 expression. In conclusion, ATOIII exposure is found to upregulate the NQO1 enzyme through a transcriptional mechanism via AHR- and NRF2- dependent mechanisms, offering valuable insights into its therapeutic mechanisms.

Pyrroloquinoline quinone protects against murine hepatitis virus strain 3-induced fulminant hepatitis by inhibiting the Keap1/Nrf2 signaling

Fulminant hepatitis (FH) is a life-threatening clinical liver syndrome characterized by substantial hepatocyte necrosis and severe liver damage. FH is typically associated with severe oxidative stress, inflammation, and mitochondrial dysfunction. Pyrroloquinoline quinone (PQQ), a naturally occurring redox cofactor, functions as an essential nutrient and antioxidant and reportedly inhibits oxidative stress and exerts potent anti-inflammatory effects. In the present study, we aimed to evaluate the therapeutic efficacy of PQQ in murine hepatitis virus strain 3 (MHV-3)-induced FH and examined the underlying mechanism. An MHV-3-induced FH mouse model was established for in vivo examination. Liver sinusoidal endothelial cells (LSECs) were used for in vitro experiments. Herein, we observed that PQQ supplementation significantly attenuated MHV-3-induced hepatic injury by suppressing inflammatory responses and reducing oxidative stress. Mechanistically, PQQ supplementation ameliorated MHV-3-induced hepatic damage by down-regulating the Keap1/Nrf2 signaling pathway in vivo and in vitro. Furthermore, Nrf2 small interfering RNA targeting LSECs abrogated the PQQ-mediated protective effects against MHV-3-related liver injury. Our results deepen our understanding of the hepatoprotective function of PQQ against MHV-3-induced liver injury and provide evidence that alleviating oxidative stress might afford a novel therapeutic strategy for treating FH.

Human NQO1 as a Selective Target for Anticancer Therapeutics and Tumor Imaging

Human NAD(P)H-quinone oxidoreductase1 (HNQO1) is a two-electron reductase antioxidant enzyme whose expression is driven by the NRF2 transcription factor highly active in the prooxidant milieu found in human malignancies. The resulting abundance of NQO1 expression (up to 200-fold) in cancers and a barely detectable expression in body tissues makes it a selective marker of neoplasms. NQO1 can catalyze the repeated futile redox cycling of certain natural and synthetic quinones to their hydroxyquinones, consuming NADPH and generating rapid bursts of cytotoxic reactive oxygen species (ROS) and H2O2. A greater level of this quinone bioactivation due to elevated NQO1 content has been recognized as a tumor-specific therapeutic strategy, which, however, has not been clinically exploited. We review here the natural and new quinones activated by NQO1, the catalytic inhibitors, and the ensuing cell death mechanisms. Further, the cancer-selective expression of NQO1 has opened excellent opportunities for distinguishing cancer cells/tissues from their normal counterparts. Given this diagnostic, prognostic, and therapeutic importance, we and others have engineered a large number of specific NQO1 turn-on small molecule probes that remain latent but release intense fluorescence groups at near-infrared and other wavelengths, following enzymatic cleavage in cancer cells and tumor masses. This sensitive visualization/quantitation and powerful imaging technology based on NQO1 expression offers promise for guided cancer surgery, and the reagents suggest a theranostic potential for NQO1-targeted chemotherapy.

Kinsenoside from Anoectochilus roxburghii (Wall.) Lindl. suppressed oxidative stress to attenuate aging-related learning and memory impairment via ERK/Nrf2 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Anoectochilusroxburghii (Wall.) Lindl. (AR), as an exceptionally valuable traditional Chinese medicine, has been widely used to treat hepatitis, cancer, diabetes, etc. But, the effects and the primary functioning element of AR on attenuating aging and aging-related learning and memory degradation has not yet been explored.

AIM OF THE STUDY

This study aimed at exploring the protective property of aqueous extract of AR (AEAR) on alleviation of aging and aging-related learning and memory impairment in vivo, and further investigating the main active ingredient and mechanism of AEAR.

MATERIALS AND METHODS

D-galactose (D-gal) induced aging mice and HT22 cells exposed with L-Glutamic acid (Glu) were used as in vivo and in vitro model, separately. The effects of AEAR on aging and aging-related learning and memory degradation were explored by using morris water maze test, immunohistochemistry staining, biochemistry assay, etc. The effects and mechanism of AEAR and Kinsenoside (Kin) on antioxidation in vitro were investigated by cell viability assay, biochemistry assay, qRT-PCR, western blotting and molecular docking studies.

RESULTS

Treatment with AEAR (containing 69.52 ± 0.85% Kin, i.g.) for 63 days, alleviated low growth rate, abnormal brain, liver and thymus index, and decline in learning and memory capability of aging mice. Meanwhile, AEAR inhibited the decreased activities of SOD and GSH-PX, the decline in the ratio of GSH to GSSG, and the increase of MDA in both serum and brain, and also promoted the Nrf2 nuclear translocation in brain of aging mice induced by D-gal. The effects of AEAR on alleviating abnormal physiological characteristics, attenuating learning and memory impairment, and inhibiting oxidative stress in aging mice was similar to or even better than that of Vc. In HT22 cells exposed with Glu, Kin increased the cell viability, up-regulated the activities of SOD and GSH-PX, enhanced the ratio of GSH to GSSG, and down-regulated MDA, which was superior to AEAR. Kin up-regulated the ratio of p-ERK1/2 to ERK1/2, promoted the Nrf2 nuclear translocation and its downstream target genes, i.e. HO-1, NQO-1, GCLC and GCLM expression at the mRNA and protein levels, which were consistent with AEAR. Further, molecular docking results also confirmed that Kin had strong binding energy with ERK1 and ERK2.

CONCLUSION

The present study indicated that Kin could alleviate the oxidative stress in aging mice via activating the ERK/Nrf2 signaling pathway, in order to attenuate aging and aging-related learning and memory impairment, as the main active ingredient of AR.

Role of NADPH Quinone Reductase 1 (NQO1) Polymorphism in Prevention, Diagnosis, and Treatment of Gastrointestinal Cancers

Most cancer deaths are related to gastrointestinal (GI) cancers. Several environmental and genetic factors are effective in the occurrence of GI cancers, such as esophageal, stomach, colorectal, liver, and pancreatic cancers. In addition to risk factors related to lifestyle, reactive oxygen species (ROS) also play a role in GI cancers, and an increase in the amount of free radicals can lead to oxidative stress and increase the probability of malignancies. NQO1 is part of the body's antioxidant defense system that protects cells against mutagenesis and carcinogenesis. NQO1 is responsible for reducing quinones to hydroquinone and preventing the generation of ROS by catalyzing the reaction. The existence of single nucleotide polymorphisms (SNPs) of NADPH Quinone Reductase 1 (NQO1), such as 609C>T NQO1, leads to a decrease in NQO1 enzyme activity. Some NQO1 polymorphisms may increase the risk of gastrointestinal cancer. So, the C609T polymorphism in the NQO1 gene has been found to be effective in causing gastrointestinal cancers. On the other hand, it is very important to know the role of biomarkers in the prognosis and management of cancer treatment. Therefore, this study investigated the role of NQO1 as a biomarker in the management of gastrointestinal cancers (prevention, diagnosis and treatment).

Anticancer effects of cell-free culture supernatant of Escherichia coli in bladder cancer cell line: New insight into the regulation of inflammation

Bladder cancer (BC) is the 10th most common malignancy in worldwide, with substantial mortality and morbidity if not treated effectively. According to various research, inflammatory circumstances majorly impact the microenvironment of bladder cancer, and the chronic presence of cytokines and chemokines promotes tumor progression. In this investigation, we explored the impact of cell-free culture supernatant ofEscherichia colistrain 536 on inflammatory cytokines and chemokines in bladder cancer model microarray data (GSE162251). Then we examined in silico outcomes on human bladder cancer cell line 5637 to verify and extrapolate findings. This investigation revealed for the first time that this compound has potent suppressor effects on interleukin 1 beta (IL-1β), C-C motif chemokine ligand 2 (CCL2), and C-X3-C motif chemokine ligand 1 (CX3CL1) gene expression as well as increased NAD(P)H quinone dehydrogenase 1 (NQO1), as an anti-oxidant agent, gene expression in 4, 8, and 24 h. Moreover, we confirmed that c-MYC, a member of the MYC proto-oncogene family, gene expression reduced in 5637 cells in 4 h and then followed up its expression in 8 and 24 h. In addition, our investigation demonstrated that the supernatant raised the BCL2-Associated X Protein/B-cell lymphoma 2 (BAX/BCL2) ratio, and subsequent flow cytometry analysis demonstrated that the supernatant induction apoptosis and necrosis. In conclusion, our findings demonstrate that this compound is a potential candidate for the suppression of bladder cancer progression.

PCB126 exposure during pregnancy alters maternal and fetal gene expression

Polychlorinated biphenyls (PCBs) are organic pollutants that can have lasting impacts on offspring health. Here, we sought to examine maternal and fetal gene expression differences of aryl hydrocarbon receptor (AHR)-regulated genes in a mouse model of prenatal PCB126 exposure. Female mice were bred and gavaged with 1 µmole/kg bodyweight PCB126 or vehicle control on embryonic days 0 and 14, and maternal and fetal tissues were collected on embryonic day 18.5. Total RNAs were isolated, and gene expression levels were analyzed in both maternal and fetal tissues using the NanoString nCounter system. Interestingly, we found that the expression levels of cytochrome P450 (Cyp)1a1 and Cyp1b1 were significantly increased in response to PCB exposure in the tested maternal and fetal tissues. Furthermore, PCB exposure altered the expression of several other genes related to energy balance, oxidative stress, and epigenetic regulation in a manner that was less consistent across tissue types. These results indicate that maternal PCB126 exposure significantly alters gene expression in both developing fetuses and pregnant dams, and such changes vary in intensity and expressivity depending on tissue type. The altered gene expression may provide insights into pathophysiological mechanisms by which in utero PCB exposures contribute to PCB-induced postnatal metabolic diseases.

Targeting Nrf2 for ferroptosis-based therapy: Implications for overcoming ferroptosis evasion and therapy resistance in cancer

Ferroptosis is a newly discovered form of programmed cell death caused by redox-active iron-mediated lipid peroxidation. Ferroptosis exhibits a unique morphological phenotype resulting from oxidative damage to membrane lipids. Ferroptosis induction has been shown to be effective in treating human cancers that rely on lipid peroxidation repair pathways. Nuclear factor erythroid 2-related factor 2 (Nrf2) can control the regulatory pathways of ferroptosis, which involve genes associated with glutathione biosynthesis, antioxidant responses, and lipid and iron metabolism. Resistant cancer cells often utilize Nrf2 stabilization by Keap1 inactivation or other somatic alterations in the genes from the Nrf2 pathway, which can confer resistance to ferroptosis induction and other therapies. However, pharmacological inactivation of the Nrf2 pathway can sensitize cancer cells to ferroptosis induction. Inducing lipid peroxidation and ferroptosis through regulating the Nrf2 pathway is a promising strategy for enhancing the anticancer effects of chemotherapy and radiation therapy in therapy-resistant human cancers. Despite promising preliminary studies, clinical trials in human cancer therapy have not yet been realized. A deeper understanding of their exact processes and efficacies in various cancers remains unsolved. Therefore, this article aims to summarize the regulatory mechanisms of ferroptosis, their modulation by Nrf2, and the potential of targeting Nrf2 for ferroptosis-based cancer therapy.

Transcriptomic and Functional Analyses Reveal the Different Roles of Vitamins C, E, and K in Regulating Viral Infections in Maize

Maize lethal necrosis (MLN), one of the most important maize viral diseases, is caused by maize chlorotic mottle virus (MCMV) infection in combination with a potyvirid, such as sugarcane mosaic virus (SCMV). However, the resistance mechanism of maize to MLN remains largely unknown. In this study, we obtained isoform expression profiles of maize after SCMV and MCMV single and synergistic infection (S + M) via comparative analysis of SMRT- and Illumina-based RNA sequencing. A total of 15,508, 7567, and 2378 differentially expressed isoforms (DEIs) were identified in S + M, MCMV, and SCMV libraries, which were primarily involved in photosynthesis, reactive oxygen species (ROS) scavenging, and some pathways related to disease resistance. The results of virus-induced gene silencing (VIGS) assays revealed that silencing of a vitamin C biosynthesis-related gene, ZmGalDH or ZmAPX1, promoted viral infections, while silencing ZmTAT or ZmNQO1, the gene involved in vitamin E or K biosynthesis, inhibited MCMV and S + M infections, likely by regulating the expressions of pathogenesis-related (PR) genes. Moreover, the relationship between viral infections and expression of the above four genes in ten maize inbred lines was determined. We further demonstrated that the exogenous application of vitamin C could effectively suppress viral infections, while vitamins E and K promoted MCMV infection. These findings provide novel insights into the gene regulatory networks of maize in response to MLN, and the roles of vitamins C, E, and K in conditioning viral infections in maize.

Silver nanoparticles induced testicular damage targeting NQO1 and APE1 dysregulation, apoptosis via Bax/Bcl-2 pathway, fibrosis via TGF-β/α-SMA upregulation in rats

In medicine, silver nanoparticles (AgNPs) are employed often. They do, however, have negative impacts, particularly on the reproductive organs. This research aimed to assess AgNP impact on the testis and the possible intracellular mechanisms to induce testicular deteriorations in rats at various concentrations and different time intervals. Sprague Dawley rats (n = 40) were allocated into four equal groups: the control one, and three other groups injected intra-peritoneally with AgNP solution 0.25, 0.5, and 1 mg/kg b.w. respectively for 15 and 30 days. Our findings revealed that AgNPs reduced body and testicular weights, estradiol (E2) and testosterone (T) hormone levels, and sperm parameters while elevating the nitric oxide and malondialdehyde levels with inhibition of reduced glutathione contents in testicular tissue. Interestingly, AgNPs significantly upregulated the testicular inducible nitric oxide synthase, B cell lymphoma 2 (Bcl-2)-associated X, transforming growth factor, and alpha-smooth muscle actin (α-SMA) expression levels. However, apurinic/apyrimidinic endo deoxyribonuclease 1 (APE1), NAD (P) H quinone dehydrogenase 1 (NQO1), and Bcl-2 expression levels were all downregulated indicating exhaustion of body antioxidant and repairing defense mechanisms in testicles in comparison with the control rats. Various histological alterations were also detected which dramatically increased in rats sacrificed after 30 days such as loss of the lining cells of seminiferous tubules with no spermatozoa and tubular irregularities associated with thickening of their basement membranes. Immunolabeling implicated in the apoptotic pathway revealed a negative expression of Bcl-2 and marked immunoreactivity for caspase-3 after 30 days of AgNP treatment in comparison to the control rats. To our knowledge, there have been no previous publications on the role of the α-SMA, APE1, and NQO1 genes in the molecular pathogenesis of AgNP testicular cytotoxicity following AgNP acute and chronic exposure.

Stress Activated MAP Kinases and Cyclin-Dependent Kinase 5 Mediate Nuclear Translocation of Nrf2 via Hsp90α-Pin1-Dynein Motor Transport Machinery

Non-lethal low levels of oxidative stress leads to rapid activation of the transcription factor nuclear factor-E2-related factor 2 (Nrf2), which upregulates the expression of genes important for detoxification, glutathione synthesis, and defense against oxidative damage. Stress-activated MAP kinases p38, ERK, and JNK cooperate in the efficient nuclear accumulation of Nrf2 in a cell-type-dependent manner. Activation of p38 induces membrane trafficking of a glutathione sensor neutral sphingomyelinase 2, which generates ceramide upon depletion of cellular glutathione. We previously proposed that caveolin-1 in lipid rafts provides a signaling hub for the phosphorylation of Nrf2 by ceramide-activated PKCζ and casein kinase 2 to stabilize Nrf2 and mask a nuclear export signal. We further propose a mechanism of facilitated Nrf2 nuclear translocation by ERK and JNK. ERK and JNK phosphorylation of Nrf2 induces the association of prolyl cis/trans isomerase Pin1, which specifically recognizes phosphorylated serine or threonine immediately preceding a proline residue. Pin1-induced structural changes allow importin-α5 to associate with Nrf2. Pin1 is a co-chaperone of Hsp90α and mediates the association of the Nrf2-Pin1-Hsp90α complex with the dynein motor complex, which is involved in transporting the signaling complex to the nucleus along microtubules. In addition to ERK and JNK, cyclin-dependent kinase 5 could phosphorylate Nrf2 and mediate the transport of Nrf2 to the nucleus via the Pin1-Hsp90α system. Some other ERK target proteins, such as pyruvate kinase M2 and hypoxia-inducible transcription factor-1, are also transported to the nucleus via the Pin1-Hsp90α system to modulate gene expression and energy metabolism. Notably, as malignant tumors often express enhanced Pin1-Hsp90α signaling pathways, this provides a potential therapeutic target for tumors.

Adipose-Derived Mesenchymal Stem Cells Alleviate Hypertrophic Scar by Inhibiting Bioactivity and Inducing Apoptosis in Hypertrophic Scar Fibroblasts

Background: As a fibrotic disease with a high incidence, the pathogenesis of hypertrophic scarring is still not fully understood, and the treatment of this disease is also challenging. In recent years, human adipose-derived mesenchymal stem cells (AD-MSCs) have been considered an effective treatment for hypertrophic scars. This study mainly explored whether the therapeutic effect of AD-MSCs on hypertrophic scars is associated with oxidative-stress-related proteins. Methods: AD-MSCs were isolated from adipose tissues and characterized through flow cytometry and a differentiation test. Afterwards, coculture, cell proliferation, apoptosis, and migration were detected. Western blotting and a quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect oxidative stress-related genes and protein expression in hypertrophic scar fibroblasts (HSFs). Flow cytometry was used to detect reactive oxygen species (ROS). A nude mouse animal model was established; the effect of AD-MSCs on hypertrophic scars was observed; and hematoxylin and eosin staining, Masson's staining, and immunofluorescence staining were performed. Furthermore, the content of oxidative-stress-related proteins, including nuclear factor erythroid-2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), B-cell lymphoma 2(Bcl2), Bcl2-associated X(BAX) and caspase 3, was detected. Results: Our results showed that AD-MSCs inhibited HSFs' proliferation and migration and promoted apoptosis. Moreover, after coculture, the expression of antioxidant enzymes, including HO-1, in HSFs decreased; the content of reactive oxygen species increased; and the expression of Nrf2 decreased significantly. In animal experiments, we found that, at 14 days after injection of AD-MSCs into human hypertrophic scar tissue blocks that were transplanted onto the dorsum of nude mice, the weight of the tissue blocks decreased significantly. Hematoxylin and eosin staining and Masson's staining demonstrated a rearrangement of collagen fibers. We also found that Nrf2 and antioxidant enzymes decreased significantly, while apoptotic cells increased after AD-MSC treatment. Conclusions: Our results demonstrated that AD-MSCs efficiently cured hypertrophic scars by promoting the apoptosis of HSFs and by inhibiting their proliferation and migration, which may be related to the inhibition of Nrf2 expression in HSFs, suggesting that AD-MSCs may provide an alternative therapeutic approach for the treatment of hypertrophic scars.

Nrf1 is an indispensable redox-determining factor for mitochondrial homeostasis by integrating multi-hierarchical regulatory networks

To defend against a vast variety of challenges in oxygenated environments, all life forms have evolutionally established a set of antioxidants, detoxification, and cytoprotective systems during natural selection and adaptive survival, to maintain cell redox homeostasis and organ integrity in the healthy development and growth. Such antioxidant defense systems are predominantly regulated by two key transcription factors Nrf1 and Nrf2, but the underlying mechanism(s) for their coordinated redox control remains elusive. Here, we found that loss of full-length Nrf1 led to a dramatic increase in reactive oxygen species (ROS) and oxidative damages in Nrf1α-∕- cells, and this increase was not eliminated by drastic elevation of Nrf2, even though the antioxidant systems were also substantially enhanced by hyperactive Nrf2. Further studies revealed that the increased ROS production in Nrf1α-∕- resulted from a striking impairment in the mitochondrial oxidative respiratory chain and its gene expression regulated by nuclear respiratory factors, called αPalNRF1 and GABPNRF2. In addition to the antioxidant capacity of cells, glycolysis was greatly augmented by aberrantly-elevated Nrf2, so to partially relieve the cellular energy demands, but aggravate its mitochondrial stress. The generation of ROS was also differentially regulated by Nrf1 and Nrf2 through miR-195 and/or mIR-497-mediated UCP2 pathway. Consequently, the epithelial-mesenchymal transformation (EMT) of Nrf1α-∕- cells was activated by putative ROS-stimulated signaling via MAPK, HIF1α, NF-ƙB, PI3K and AKT, all players involved in cancer development and progression. Taken together, it is inferable that Nrf1 acts as a potent integrator of redox regulation by multi-hierarchical networks.

Structural Insights into the NAD(P)H:Quinone Oxidoreductase from Phytophthora capsici

Soluble quinone oxidoreductases catalyze transfer of electrons from NADPH to quinones. Transfer of electrons is essential for detoxification of synthetic compounds. Here, we present the crystal structure of a NADPH-dependent QOR from Phytophthora capsici (Pc) complexed with NADPH at 2.4 Å resolution. The enzyme exhibits a bi-modular architecture, containing a NADPH-binding groove and a substrate-binding pocket in each subunit. In the crystal, each asymmetric unit of PcQOR contains two molecules stabilized by intermolecular interactions. Gel filtration and ultracentrifugation analyses reveal that it functions as a tetramer in solution. Alignment of homologous structures exhibits a conserved topology. However, the active sites vary among the homologues, indicating differences in substrate specificities. Enzymatic assays indicate that PcQOR tends to catalyze the large substrates, like 9,10-phenanthrenequinone. Computational simulation associated with site-directed mutagenesis and enzymatic activity analysis declares a potential quinone-binding channel. The ability to reduce quinones probably helps P. capsici to detoxify some harmful chemicals encountered during invasion.

High expression of nuclear NRF2 combined with NFE2L2 alterations predicts poor prognosis in esophageal squamous cell carcinoma patients

Nuclear factor erythroid-2 related factor-2 (NFE2L2 or NRF2) is a frequently mutated gene in esophageal squamous cell carcinoma (ESCC). However, the roles of NFE2L2 alterations in ESCC remain elusive. In order to elucidate this issue, 130 ESCC patients who underwent esophagectomy were enrolled. The majority of tumor tissues were positive for NRF2, which was significantly enriched in the nucleus of the primary tumor tissues compared with the noncancerous mucosae. Primary ESCC tumors positive for NRF2 tended to be positive for NAD(P)H quinone oxidoreductase 1 (NQO1) as the downstream target of NRF2. There was a positive correlation between NRF2 and NQO1 expression level in primary tumors. NQO1 staining in primary tumors with NRF2 nuclear expression was significantly stronger than that with NRF2 cytoplasmic expression. In addition, high concordance for the status of NRF2 expression between primary tumors and corresponding metastatic lesions was observed. Next, we found high expression of nuclear NRF2 (the proportion of nuclear NRF2 expression >20% or nuclear NRF2 immunohistochemistry score >20) predicted shorter overall survival in patients with dual-positive expression of NRF2 and NQO1. Captured-based targeted sequencing revealed that NFE2L2 somatic alterations were observed in 52.8% of ESCC patients with dual-positive expression of NRF2 and NQO1. NFE2L2 amplification and mutations within the DLG/ETGE motifs were seen more frequently in ESCC tumors with nuclear or nucleocytoplasmic expression of NRF2 compared with those with cytoplasmic expression of NRF2. We also found high expression of nuclear NRF2 plus the status of NFE2L2 alteration exhibited high performance in predicting prognosis of ESCC patients. Our study demonstrated that high nuclear NRF2 expression and NFE2L2 alterations were associated with poor prognosis of ESCC patients. These findings suggest that NRF2 signaling pathway might play vital roles in ESCC malignancy and the aberrant activation of NRF2 pathway predicts unfavorable prognosis in ESCC.

Epigenetic Therapeutics Targeting NRF2/KEAP1 Signaling in Cancer Oxidative Stress

The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) and its negative regulator kelch-like ECH-associated protein 1 (KEAP1) regulate various genes involved in redox homeostasis, which protects cells from stress conditions such as reactive oxygen species and therefore exerts beneficial effects on suppression of carcinogenesis. In addition to their pivotal role in cellular physiology, accumulating innovative studies indicated that NRF2/KEAP1-governed pathways may conversely be oncogenic and cause therapy resistance, which was profoundly modulated by epigenetic mechanism. Therefore, targeting epigenetic regulation in NRF2/KEAP1 signaling is a potential strategy for cancer treatment. In this paper, the current knowledge on the role of NRF2/KEAP1 signaling in cancer oxidative stress is presented, with a focus on how epigenetic modifications might influence cancer initiation and progression. Furthermore, the prospect that epigenetic changes may be used as therapeutic targets for tumor treatment is also investigated.

Targeting HIF-1α Function in Cancer through the Chaperone Action of NQO1: Implications of Genetic Diversity of NQO1

HIF-1α is a master regulator of oxygen homeostasis involved in different stages of cancer development. Thus, HIF-1α inhibition represents an interesting target for anti-cancer therapy. It was recently shown that the HIF-1α interaction with NQO1 inhibits proteasomal degradation of the former, thus suggesting that targeting the stability and/or function of NQO1 could lead to the destabilization of HIF-1α as a therapeutic approach. Since the molecular interactions of NQO1 with HIF-1α are beginning to be unraveled, in this review we discuss: (1) Structure–function relationships of HIF-1α; (2) our current knowledge on the intracellular functions and stability of NQO1; (3) the pharmacological modulation of NQO1 by small ligands regarding function and stability; (4) the potential effects of genetic variability of NQO1 in HIF-1α levels and function; (5) the molecular determinants of NQO1 as a chaperone of many different proteins including cancer-associated factors such as HIF-1α, p53 and p73α. This knowledge is then further discussed in the context of potentially targeting the intracellular stability of HIF-1α by acting on its chaperone, NQO1. This could result in novel anti-cancer therapies, always considering that the substantial genetic variability in NQO1 would likely result in different phenotypic responses among individuals.

Role of Nrf2 Signaling Cascade in Breast Cancer: Strategies and Treatment

Breast cancer is the second leading cancer among all types of cancers. It accounts for 12% of the total cases of cancers. The complex and heterogeneous nature of breast cancer makes it difficult to treat in advanced stages. The expression of various enzymes and proteins is regulated by several molecular pathways. Oxidative stress plays a vital role in cellular events that are generally regulated by nuclear factor erythroid 2-related factor 2 (Nrf2). The exact mechanism of Nrf2 behind cytoprotective and antioxidative properties is still under investigation. In healthy cells, Nrf2 expression is lower, which maintains antioxidative stress; however, cancerous cells overexpress Nrf2, which is associated with various phenomena, such as the development of drug resistance, angiogenesis, development of cancer stem cells, and metastasis. Aberrant Nrf2 expression diminishes the toxicity and potency of therapeutic anticancer drugs and provides cytoprotection to cancerous cells. In this article, we have discussed the attributes associated with Nrf2 in the development of drug resistance, angiogenesis, cancer stem cell generation, and metastasis in the specific context of breast cancer. We also discussed the therapeutic strategies employed against breast cancer exploiting Nrf2 signaling cascades.

Review on NAD(P)H dehydrogenase quinone 1 (NQO1) pathway

NQO1 is an enzyme present in humans which is encoded by NQO1 gene. It is a protective antioxidant agent, versatile cytoprotective agent and regulates the oxidative stresses of chromatin binding proteins for DNA damage in cancer cells. The oxidization of cellular pyridine nucleotides causes structural alterations to NQO1 and changes in its capacity to binding of proteins. A strategy based on NQO1 to have protective effect against cancer was developed by organic components to enhance NQO1 expression. The quinone derivative compounds like mitomycin C, RH1, E09 (Apaziquone) and β-lapachone causes cell death by NQO1 reduction of two electrons. It was also known to be overexpressed in various tumor cells of breast, lung, cervix, pancreas and colon when it was compared with normal cells in humans. The mechanism of NQO1 by the reduction of FAD by NADPH to form FADH2 is by two ways to inhibit cancer cell development such as suppression of carcinogenic metabolic activation and prevention of carcinogen formation. The NQO1 exhibit suppression of chemical-mediated carcinogenesis by various properties of NQO1 which includes, detoxification of quinone scavenger of superoxide anion radical, antioxidant enzyme, protein stabilizer. This review outlines the NQO1 structure, mechanism of action to inhibit the cancer cell, functions of NQO1 against oxidative stress, drugs acting on NQO1 pathways, clinical significance.

Identification of the Signature Genes and Network of Reactive Oxygen Species Related Genes and DNA Repair Genes in Lung Adenocarcinoma

Reactive Oxygen Species (ROS) are present in excess amounts in patients with tumors, and these ROS can kill and destroy tumor cells. Therefore, tumor cells upregulate ROS-related genes to protect them and reduce their destructing effects. Cancer cells already damaged by ROS can be repaired by expressing DNA repair genes consequently promoting their proliferation. The present study aimed to identify the signature genes of and regulating network of ROS-related genes and DNA repair genes in lung adenocarcinoma (LUAD) using transcriptomic data of public databases. The LUAD transcriptome data in the TCGA database and gene expressions from Gene Expression Omnibus (GEO) were analyzed and samples were clustered into 5 ROS-related categories and 6 DNA repair categories. Survival analysis revealed a significant difference in patient survival between the two classification methods. In addition, the samples corresponding to the two categories overlap, thus, the gene expression profile of the same sample with different categories and survival prognosis was further explored, and the connection between ROS-related and DNA repair genes was investigated. The interactive sample recombination classification was used, revealing that the patient's prognosis was worse when the ROS-related and DNA repair genes were expressed at the same time. The further research on the potential regulatory network of the two categories of genes and the correlation analysis revealed that ROS-related genes and DNA repair genes have a mutual regulatory relationship. The ROS-related genes namely NQO1, TXNRD1, and PRDX4 could establish links with other DNA repair genes through the DNA repair gene NEIL3, thereby balancing the level of ROS. Therefore, targeting ROS-related genes and DNA repair genes might be a promising strategy in the treatment of LUAD. Finally, a survival prognostic model of ROS-related genes and DNA repair genes was established (TERT, PRKDC, PTTG1, SMUG1, TXNRD1, CAT, H2AFX, and PFKP). The risk score obtained from our survival prognostic model could be used as an independent prognostic factor in LUAD patients.

Ferroptosis: regulation by competition between NRF2 and BACH1 and propagation of the death signal

Ferroptosis is triggered by a chain of intracellular labile iron-dependent peroxidation of cell membrane phospholipids. Ferroptosis is important not only as a cause of ischaemic and neurodegenerative diseases but also as a mechanism of cancer suppression, and a better understanding of its regulatory mechanism is required. It has become clear that ferroptosis is finely controlled by two oxidative stress-responsive transcription factors, NRF2 (NF-E2-related factor 2) and BACH1 (BTB and CNC homology 1). NRF2 and BACH1 inhibit and promote ferroptosis, respectively, by activating or suppressing the expression of genes in the major regulatory pathways of ferroptosis: intracellular labile iron metabolism, the GSH (glutathione) -GPX4 (glutathione peroxidase 4) pathway and the FSP1 (ferroptosis suppressor protein 1)-CoQ (coenzyme Q) pathway. In addition to this, NRF2 and BACH1 control ferroptosis through the regulation of lipid metabolism and cell differentiation. This multifaceted regulation of ferroptosis by NRF2 and BACH1 is considered to have been acquired during the evolution of multicellular organisms, allowing the utilization of ferroptosis for maintaining homeostasis, including cancer suppression. In terms of cell-cell interaction, it has been revealed that ferroptosis has the property of propagating to surrounding cells along with lipid peroxidation. The regulation of ferroptosis by NRF2 and BACH1 and the propagation phenomenon could be used to realize anticancer cell therapy in the future. In this review, these points will be summarized and discussed.

Investigation of Chemopreventive and Antiproliferative Potential of Dicliptera roxburghiana

CONTEXT

Carcinogenesis causes much human misery. It is a process involving multistage alterations. Medicinal plants are candidates for beneficial anticancer agents.

OBJECTIVES

Investigation of anticancer proficiencies of the plant Dicliptera roxburghiana.

MATERIAL AND METHODS

Crude extract and derived fractions were inspected for their inhibitory potential against nuclear factor KB (NFκB), nitric oxide synthase inhibition, aromatase inhibition and induction of quinone reductase 1 (QR 1). Antiproliferative activity was determined by using various cancer cell lines for example hormone responsive breast cancer cell line MCF-7, estrogen receptor negative breast cancer cell line MDA-MB-231, murine hepatoma cells Hepa 1c1c7, human neuroblastoma cells SK-N-SH and neuroblastoma cells MYCN-2.

RESULTS

Ethyl acetate and n-butanol fractions of D. roxburghiana were strongly active against NFκB with IC₅₀ of 16.6 ± 1.3 and 8.4 ± 0.7 µg/ml respectively with 100% survival. Chloroform fraction of the plant exhibited an induction ratio of 2.4 ± 0.09 with CD value of 17.7 µg/ml. Regarding the nitrite assay, the n-hexane fraction exhibited significant inhibition of NO activity with IC₅₀ of 17.8 ± 1.25 µg/ml. The n-butanol fraction exhibited strong antiproliferative activity against IcIc-7 cell lines with IC₅₀ values of 13.6 ± 1.91 µg/ml; against MYCN-2 a cytotoxic effect developed with dose dependence, with IC₅₀ of 12.6 ± 1.24 µg/ml. In antiproliferative activity against SK-N-SH cell lines, chloroform, ethyl acetate and n-butanol fractions were efficiently active with IC₅₀ values of 11.2 ± 0.84, 14.6 ± 1.71 and 16.3 ± 1.57 respectively.

DISCUSSION AND CONCLUSION

It was demonstrated that various fractions of D. roxburghiana displayed appreciable anticancer characteristics and could be a potent source for the development of anticancer leads.

Roles of NAD(P)H:quinone Oxidoreductase 1 in Diverse Diseases

NAD(P)H:quinone oxidoreductase (NQO) is an antioxidant flavoprotein that catalyzes the reduction of highly reactive quinone metabolites by employing NAD(P)H as an electron donor. There are two NQO enzymes—NQO1 and NQO2—in mammalian systems. In particular, NQO1 exerts many biological activities, including antioxidant activities, anti-inflammatory effects, and interactions with tumor suppressors. Moreover, several recent studies have revealed the promising roles of NQO1 in protecting against cardiovascular damage and related diseases, such as dyslipidemia, atherosclerosis, insulin resistance, and metabolic syndrome. In this review, we discuss recent developments in the molecular regulation and biochemical properties of NQO1, and describe the potential beneficial roles of NQO1 in diseases associated with oxidative stress.

Novel Corneal Protein Biomarker Candidates Reveal Iron Metabolic Disturbance in High Myopia Eyes

Myopia is a major public health concern with increasing global prevalence and is the leading cause of vision loss and complications. The potential role of the cornea, a substantial component of refractive power and the protective fortress of the eye, has been underestimated in the development of myopia. Our study acquired corneal stroma tissues from myopic patients undergoing femtosecond laser-assisted small incision lenticule extraction (SMILE) surgery and investigated the differential expression of circulating proteins between subjects with low and high myopia by means of high-throughput proteomic approaches—the quantitative tandem mass tag (TMT) labeling method and parallel reaction monitoring (PRM) validation. Across all corneal stroma tissue samples, a total of 2,455 proteins were identified qualitatively and quantitatively, 103 of which were differentially expressed between those with low and high myopia. The differentially abundant proteins (DAPs) between the groups of stroma samples mostly demonstrated catalytic activity and molecular function regulator and transporter activity and participated in metabolic processes, biological regulation, response to stimulus, and so forth. Pathway enrichment showed that mineral absorption, ferroptosis, and HIF-1 signaling pathways were activated in the human myopic cornea. Furthermore, TMT analysis and PRM validation revealed that the expression of ferritin light chain (FTL, P02792) and ferritin heavy chain (FTH1, P02794) was negatively associated with myopia development, while the expression of serotransferrin (TF, P02787) was positively related to myopia status. Overall, our results indicated that subjects with low and high myopia could have different proteomic profiles or signatures in the cornea. These findings revealed disturbances in iron metabolism and corneal oxidative stress in the more myopic eyes. Iron metabolic proteins could serve as an essential modulator in the pathogenesis of myopia.

Cross-Talk between Oxidative Stress and m6A RNA Methylation in Cancer

Oxidative stress is a state of imbalance between oxidation and antioxidation. Excessive ROS levels are an important factor in tumor development. Damage stimulation and excessive activation of oncogenes cause elevated ROS production in cancer, accompanied by an increase in the antioxidant capacity to retain redox homeostasis in tumor cells at an increased level. Although moderate concentrations of ROS produced in cancer cells contribute to maintaining cell survival and cancer progression, massive ROS accumulation can exert toxicity, leading to cancer cell death. RNA modification is a posttranscriptional control mechanism that regulates gene expression and RNA metabolism, and m⁶A RNA methylation is the most common type of RNA modification in eukaryotes. m⁶A modifications can modulate cellular ROS levels through different mechanisms. It is worth noting that ROS signaling also plays a regulatory role in m⁶A modifications. In this review, we concluded the effects of m⁶A modification and oxidative stress on tumor biological functions. In particular, we discuss the interplay between oxidative stress and m⁶A modifications.

Protective effects of cannabidiol on the membrane proteins of skin keratinocytes exposed to hydrogen peroxide via participation in the proteostasis network

Hydrogen peroxide (H₂O₂) is widely used in clinical practice due to its antiseptic properties and its ability to heal wounds. However, due to its involvement in the formation of ROS, H₂O₂ causes several side effects, including disorders of the metabolism of skin cells and the development of chronic inflammation mediated by oxidative stress. Therefore, this study evaluated the effects of cannabidiol (CBD), a phytocannabinoid known for its antioxidant and anti-inflammatory properties, on the proteome of keratinocyte membranes exposed to H₂O₂. Overall, the hydrogen peroxide caused the levels of several proteins to increase, while the treatment with CBD prevented these changes. Analysis of the protein-protein interaction network showed that the significant changes mainly involved proteins with important roles in the proteasomal activity, protein folding processes (regulatory subunit of the proteasome 26S 6A, beta proteasome subunit type 1, chaperonin 60 kDa), protein biosynthesis (40S ribosomal proteins S16, S2 and ubiquitin-S27a), regulation of the redox balance (carbonyl reductase [NADPH] 1 and NAD(P)H [quinone] 1 dehydrogenase) and cell survival (14-3-3 theta protein). Additionally, CBD reduced the total amount of MDA, 4-HNE and 4-ONE-protein adducts. Therefore, we conclude that CBD partially prevents the changes induced by hydrogen peroxide by reducing oxidative stress and maintaining proteostasis networks. Moreover, our results indicate that combination therapy with CBD may bring a promising approach in the clinical use of hydrogen peroxide by preventing its pro-oxidative and pro-inflammatory effect through potential participation of CBD in membrane mediated molecular signaling.

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CBD prevents H₂O₂-induced changes in keratinocytes membrane proteomic profile.

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Protective effect of CBD could be mediated by alterations in proteostasis network.

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CBD promotes antioxidative and pro-survival cellular response.

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CBD reduces formation of lipid peroxidation products-protein adducts.

Contribution of the Nrf2 Pathway on Oxidative Damage and Mitochondrial Failure in Parkinson and Alzheimer's Disease

The increase in human life expectancy has become a challenge to reduce the deleterious consequences of aging. Nowadays, an increasing number of the population suffer from age-associated neurodegenerative diseases including Parkinson's disease (PD) and Alzheimer's disease (AD). These disorders present different signs of neurodegeneration such as mitochondrial dysfunction, inflammation, and oxidative stress. Accumulative evidence suggests that the transcriptional factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) plays a vital defensive role orchestrating the antioxidant response in the brain. Nrf2 activation promotes the expression of several antioxidant enzymes that exert cytoprotective effects against oxidative damage and mitochondrial impairment. In this context, several studies have proposed a role of Nrf2 in the pathogenesis of PD and AD. Thus, we consider it important to summarize the ongoing literature related to the effects of the Nrf2 pathway in the context of these diseases. Therefore, in this review, we discuss the mechanisms involved in Nrf2 activity and its connection with mitochondria, energy supply, and antioxidant response in the brain. Furthermore, we will lead our discussion to identify the participation of the Nrf2 pathway in mitochondrial impairment and neurodegeneration present in PD and AD. Finally, we will discuss the therapeutic effects that the Nrf2 pathway activation could have on the cognitive impairment, neurodegeneration, and mitochondrial failure present in PD and AD.

Treatment with 5-fluoro-2-oxindole Increases the Antinociceptive Effects of Morphine and Inhibits Neuropathic Pain

The efficacy of µ-opioid receptors (MOR) in neuropathic pain is low and with numerous side effects that limited their use. Chronic neuropathic pain is also linked with emotional disorders that aggravate the sensation of pain and which treatment has not been resolved. This study investigates whether the administration of an oxindole, 5-fluoro-2-oxindole, could inhibit the nociceptive and emotional behaviors and increase the effectiveness of morphine via modulating the microglia and activating the nuclear factor erythroid-2 related factor 2 (Nrf2) signaling pathway and MOR expression. In C57BL/6 mice with neuropathic pain provoked by the total constriction of sciatic nerve we studied the effects of 10 mg/kg 5-fluoro-2-oxindole in: (i) the allodynia and hyperalgesia caused by the injury; (ii) the anxiety- and depressive-like behaviors; (iii) the local antinociceptive actions of morphine; (iv) the expression of CD11b/c (a microglial marker), the antioxidant and detoxificant enzymes Nrf2, heme oxygenase 1 (HO-1) and NAD(P)H:quinone oxidoreductase-1 (NQO1), and of MOR in the spinal cord and hippocampus. Results showed that the inhibition of the main nociceptive symptoms and the anxiety- and depressive-like behaviors induced by 5-fluoro-2-oxindole were accompanied with the suppression of microglial activation and the activation of Nrf2/HO-1/NQO1 signaling pathway in the spinal cord and/or hippocampus. This treatment also potentiated the pain-relieving activities of morphine by normalizing the reduced MOR expression. This work demonstrates the antinociceptive, anxiolytic and antidepressant effects of 5-fluoro-2-oxindole, suggests a new strategy to enhance the antinociceptive actions of morphine and proposes a new mechanism of action of oxindoles during chronic neuropathic pain.

Molecular mechanisms associated with oxidative damage in the mouse testis induced by LaCl3

China is the world's largest rare earth producer and exporter, previous studies have shown that rare earth elements can cause oxidative damage in animal testis. However, the molecular mechanisms underlying these observations have yet to be elucidated. In this paper, male mice were fed with different doses (10, 20, and 40 mg/kg BW) of LaCl₃ for 90 consecutive days, regulatory role of nuclear factor erythroid-2 related factor 2 (Nrf-2)/antioxidant response element (ARE) pathway in testicular oxidative stress induced by LaCl₃ were investigated. Analysis showed that LaCl₃ exposure could lead to severe testicular pathological changes and apoptosis in spermatogenic cells, it up-regulated the peroxidation of lipids, proteins and DNA, and induced the excessive levels of reactive oxygen species (ROS) production in mouse testis, reduced the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and glutathione S epoxide transferase (GST) as well as the glutathione (GSH) content. Furthermore, exposure to LaCl₃ also downregulated the expression of Nrf2 and its target gene products, including heme oxygenase 1 (HO-1), glutamate-cysteine ligase catalytic subunit (GCLC), NAD(P)H dehydrogenase [quinine] 1(NQO1), protein kinase C (PKC), and phosphatidylinositol 3-kinase (PI3K), but upregulated the expression of Kelch-like ECH-related protein 1 (Keap1) in damaged mouse testes. Collectively, our data imply that the oxidative damage induced by LaCl₃ in testis was related to inhibition of the Nrf-2/AREs pathway activation.

Oxidative Stress in the Tumor Microenvironment and Its Relevance to Cancer Immunotherapy

Simple Summary

Cancer cells are consistently under oxidative stress, as reflected by elevated basal level of reactive oxygen species (ROS), due to increased metabolism driven by aberrant cell growth. This feature has been exploited to develop therapeutic strategies that control tumor growth by modulating the oxidative stress in tumor cells. This review provides an overview of recent advances in cancer therapies targeting tumor oxidative stress, and highlights the emerging evidence implicating the effectiveness of cancer immunotherapies in intensifying tumor oxidative stress. The promises and challenges of combining ROS-inducing agents with cancer immunotherapy are also discussed.

Abstract

It has been well-established that cancer cells are under constant oxidative stress, as reflected by elevated basal level of reactive oxygen species (ROS), due to increased metabolism driven by aberrant cell growth. Cancer cells can adapt to maintain redox homeostasis through a variety of mechanisms. The prevalent perception about ROS is that they are one of the key drivers promoting tumor initiation, progression, metastasis, and drug resistance. Based on this notion, numerous antioxidants that aim to mitigate tumor oxidative stress have been tested for cancer prevention or treatment, although the effectiveness of this strategy has yet to be established. In recent years, it has been increasingly appreciated that ROS have a complex, multifaceted role in the tumor microenvironment (TME), and that tumor redox can be targeted to amplify oxidative stress inside the tumor to cause tumor destruction. Accumulating evidence indicates that cancer immunotherapies can alter tumor redox to intensify tumor oxidative stress, resulting in ROS-dependent tumor rejection. Herein we review the recent progresses regarding the impact of ROS on cancer cells and various immune cells in the TME, and discuss the emerging ROS-modulating strategies that can be used in combination with cancer immunotherapies to achieve enhanced antitumor effects.

NQO1 Deficiency Aggravates Renal Injury by Dysregulating Vps34/ATG14L Complex during Autophagy Initiation in Diabetic Nephropathy

Diabetic nephropathy (DN) is one of the causes of end-stage renal failure, featuring renal fibrosis. However, autophagy, a vital process for intracellular homeostasis, can counteract renal fibrosis. Moreover, NAD(P)H: quinone dehydrogenase 1 (NQO1) modulates the ratios of reduced/oxidized nicotinamide nucleotides, exerting a cytoprotective function. Here, to examine the role of NQO1 genes in DN progression, the levels of autophagy-related proteins and pro-fibrotic markers were assessed in silencing or overexpression of NQO1 in human proximal tubular cells (HK2), and C57BL/6 (wild-type) and Nqo1 knockout (KO) mice injected to streptozotocin (50 mg/kg). NQO1 deficiency impaired the autophagy process by suppressing basal expression of ClassⅢ PI 3-kinase (Vps34) and autophagy-related (ATG)14L and inducing the expressions of transforming growth factor beta (TGF-β1), Smad3, and matrix metallopeptidase9 (MMP9) in high-glucose (HG) -treated HK2 cells. Meanwhile, NQO1 overexpression increased the expression of Vps34 and ATG14L, while, reducing TGF-β1, Smad3 and MMP9 expression. In vivo, the expression of Vps34 and ATG14L were suppressed in Nqo1 KO mice indicating aggravated glomerular changes and interstitial fibrosis. Therefore, NQO1 deficiency dysregulated autophagy initiation in HK2 cells, with consequent worsened renal cell damage under HG condition. Moreover, STZ-treated Nqo1 KO mice showed that NQO1 deficiency aggravated renal fibrosis by dysregulating autophagy.

Sustained high expression of NRF2 and its target genes induces dysregulation of cellular proliferation and apoptosis is associated with arsenite-induced malignant transformation of human bronchial epithelial cells

In arsenic toxicity, activation of the erythroid 2-related factor 2 (NRF2) pathway is regarded as a driver of cancer development and progression; however, the mechanisms by which NRF2 gene expression regulates cell cycle progression and mediates pathways of cellular proliferation and apoptosis in arsenic-induced lung carcinogenesis are poorly understood. In this study, we explored the regulatory functions of NRF2 expression and its target genes in immortalized human bronchial epithelial (HBE) cells continuously exposed to 1.0 μM sodium arsenite over approximately 43 passages (22 weeks). The experimental treatment induced malignant transformation in HBE cells, characterized by increased cellular proliferation and soft agar clone formation, as well as cell migration, and accelerated cell cycle progression from G0/G1 to S phase with increased levels of cyclin E-CDK2 complex,decreased cellular apoptosis rate. Moreover, we observed a sustained increase in NRF2 protein levels and those of its target gene products (NQO1, BCL-2) with concurrently decreased expression of apoptosis-related proteins (BAX, Cleaved-caspase-3/Caspase-3 and CHOP) and increased expression of the anti-apoptotic protein MCL-1. Silencing NRF2 expression with small interfering RNA (siRNA) in arsenite-transformed (T-HBE) cells was shown to reverse the malignant phenotype. Further, siRNA silencing of NQO1 significantly decreased levels of the cyclin E-CDK2 complex, inhibiting G0/G1 to S phase cell cycle progression and transformation to the T-HBE phenotypes. This study demonstrated a novel role for the NRF2/NQO1 signaling pathway in mediating arsenite-induced cell transformation by increasing the expression of cyclin E-CDK2, and accelerating the cell cycle and cell proliferation. Arsenite promotes activation of the NRF2/BCL-2 signaling pathway inhibited CHOP increasing cellular resistance to apoptosis and further promoting malignant transformation.

Jujube (Ziziphus jujuba Mill.) Protects Hepatocytes against Alcohol-Induced Damage through Nrf2 Activation

This study aimed at evaluating the cytoprotective activity of jujube water extract (JWE) against alcohol-induced oxidative stress via the activation of the Nrf2 pathway in HepG2 cells. JWE had various phenolic compounds, and the vanillic acid content was the highest in the extract. To determine the cytoprotective effect of JWE against alcohol-induced damage, hepatocytes were treated with JWE and 3% ethanol. JWE (100 μg/mL) markedly increased cell viability by approximately 100% in a dose-dependent manner. Moreover, JWE attenuated the production of malondialdehyde, reactive oxygen species, aspartate, and alanine aminotransferase and the depletion of glutathione. Moreover, JWE enhanced the expression of antioxidant defense enzymes including heme oxygenase-1, NADPH quinone oxidoreductase 1, and γ-glutamate-cysteine ligase catalytic against alcohol-induced oxidative damage in hepatocytes via the activation of Nrf2. Taken together, JWE possesses the protective effect against alcohol-induced oxidative injury in hepatocytes through the upregulation of the Nrf2 signaling pathway. Therefore, jujube fruit might have the potential to improve alcohol-related liver problems.

Ferroptosis-Related Flavoproteins: Their Function and Stability

Ferroptosis has been described recently as an iron-dependent cell death driven by peroxidation of membrane lipids. It is involved in the pathogenesis of a number of diverse diseases. From the other side, the induction of ferroptosis can be used to kill tumor cells as a novel therapeutic approach. Because of the broad clinical relevance, a comprehensive understanding of the ferroptosis-controlling protein network is necessary. Noteworthy, several proteins from this network are flavoenzymes. This review is an attempt to present the ferroptosis-related flavoproteins in light of their involvement in anti-ferroptotic and pro-ferroptotic roles. When available, the data on the structural stability of mutants and cofactor-free apoenzymes are discussed. The stability of the flavoproteins could be an important component of the cellular death processes.

A dendrimer-functionalized turn-on fluorescence probe based on enzyme-activated debonding feature of azobenzene linkage

The hypoxic feature of tumors has led to researchers developing hypoxia-activated prodrugs and probes that leverage oxidoreductases overexpressed in tumor tissues.

The Antinociceptive, Antioxidant and Anti-Inflammatory Effects of 5-Fluoro-2-Oxindole during Inflammatory Pain

Recent studies demonstrate that 5-fluoro-2-oxindole inhibits neuropathic pain but the antinociceptive actions of this drug and its effects on the plasticity, oxidative and inflammatory changes induced by peripheral inflammation as well as on the effects and expression of µ-opioid receptors (MOR) have not been evaluated. In C57BL/6 male mice with inflammatory pain provoked by the subplantar administration of complete Freund’s adjuvant (CFA), we evaluated: (1) the antinociceptive actions of 5-fluoro-2-oxindole and its reversion with the HO-1 inhibitor, tin protoporphyrin IX (SnPP); (2) the effects of 5-fluoro-2-oxindole in the protein levels of mitogen-activated protein kinase (MAPK), Nrf2, NADPH quinone oxidoreductase1 (NQO1), heme oxygenase 1 (HO-1), oxidative stress marker (4-hydroxy-2-nonenal; 4-HNE), inducible nitric oxide synthase (NOS2), microglial markers (CD11b/c and IBA-1), and MOR in the spinal cord and/or paw of animals with inflammatory pain; (3) the antinociceptive effects of morphine in 5-fluoro-2-oxindole pre-treated animals. Treatment with 5 and 10 mg/kg of 5-fluoro-2-oxindole inhibited the allodynia and hyperalgesia induced by CFA in a different, time-dependent manner. These effects were reversed by SnPP. Treatment with 5-fluoro-2-oxindole increased the expression of NQO1, HO-1 and MOR and inhibited the CFA-induced upregulation of phosphorylated MAPK, 4-HNE, NOS2, CD11b/c and IBA-1 in spinal cords and/or paws. The local effects of morphine were improved with 5-fluoro-2-oxindole. This work reveals that 5-fluoro-2-oxindole inhibits the plasticity, oxidative and inflammatory responses provoked by peripheral inflammation and potentiates the antinociceptive effects of morphine. Thus, treatment with 5-fluoro-2-oxindole alone and/or combined with morphine are two remarkable new procedures for chronic inflammatory pain management.

The potential roles of NAD(P)H:quinone oxidoreductase 1 in the development of diabetic nephropathy and actin polymerization

Diabetic nephropathy (DN) is a major complication of diabetes mellitus. NAD(P)H:quinone oxidoreductase 1 (NQO1) is an antioxidant enzyme that has been involved in the progression of several kidney injuries. However, the roles of NQO1 in DN are still unclear. We investigated the effects of NQO1 deficiency in streptozotocin (STZ)-induced DN mice. NQO1 was upregulated in the glomerulus and podocytes under hyperglycemic conditions. NQO1 knockout (NKO) mice showed more severe changes in blood glucose and body weight than WT mice after STZ treatment. Furthermore, STZ-mediated pathological parameters including glomerular injury, blood urea nitrogen levels, and foot process width were more severe in NKO mice than WT mice. Importantly, urine albumin-to-creatinine ratio (ACR) was higher in healthy, non-treated NKO mice than WT mice. ACR response to STZ or LPS was dramatically increased in the urine of NKO mice compared to vehicle controls, while it maintained a normal range following treatment of WT mice. More importantly, we found that NQO1 can stimulate actin polymerization in an in vitro biochemical assay without directly the accumulation on F-actin. In summary, NQO1 has an important role against the development of DN pathogenesis and is a novel contributor in actin reorganization via stimulating actin polymerization.

Tanshinone IIA attenuates acetaminophen-induced hepatotoxicity through HOTAIR-Nrf2-MRP2/4 signaling pathway

Tanshinone IIA (Tan IIA), an active component in S. miltiorrhiza, has been reported to have excellent antioxidant and detoxifying activity. Here, we prove that Tan IIA attenuates acetaminophen-induced hepatotoxicity from a pharmacokinetic perspective. Compared with acetaminophen (APAP, 200 mg/kg) treated mice, Tan IIA pretreatment (30 mg/kg/d) not only reduced the plasma level of the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI) but also increased its bile level. After Tan IIA pretreatment, significant induction of nuclear factor E2-related factor 2 (Nrf2), multidrug resistance-associated protein 2 (Mrp2), and multidrug resistance-associated protein 4 (Mrp4) mRNA and protein expression was detected in Nrf2+/+ mouse liver, however, much lower increase of Mrp2 and Mrp4 mRNA and protein expression was observed in Nrf2-/- mouse liver. Luciferase reporter and chromatin immunoprecipitation assays demonstrated that Nrf2 bounds to antioxidant responsive elements (AREs) of the MRP2 and MRP4 promoter, thus regulating the expression of MRP2 and MRP4. in vitro experiments revealed that Tan IIA increase Nrf2, MRP2, and MRP4 expression through a mechanism of inhibiting the expression of HOX transcript antisense RNA (HOTAIR) which belongs to long non-coding RNAs. Collectively, the present results demonstrated that Tan IIA could protect against APAP-induced hepatotoxicity by altering the pharmacokinetic characteristics of APAP and its metabolites via HOTAIR-Nrf2-MRP2/4 signaling pathway, and HOTAIR plays a pivotal role in the MRP2 and MRP4 expression regulated by Nrf2.

The expression of zebrafish NAD(P)H:quinone oxidoreductase 1(nqo1) in adult organs and embryos

NQO1, NAD(P)H: quinone oxidoreductase 1, was first identified in rat and its role has been extensively studied. Even the roles of NQO1 in the maintenance of physiological function and disease were largely addressed, whether the tissue specific functions of the NQO1 in organ development remains unknown. In the current study, we identified two NQO1 isoforms (isoform 1 and isoform 2) and examined the expression of nqo1 variants in adult zebrafish organs and embryos at different stages. In adult organs, RT-PCR result indicated that nqo1 variant 1 was mainly expressed in stomach and intestine, while nqo1 variant 2 was expressed in all organs investigated except for heart. Further, RT-PCR result showed that the nqo1 variant 1 and variant 2 were expressed at all the embryonic stages, but nqo1 variant 1 expression level was much lower than that of nqo1 variant 2. To specifically examine the expression pattern of these two different nqo1 variants, we did whole mount in situ hybridization and the results demonstrated that, both of them were maternally expressed at 8-cell stage, and they were all expressed ubiquitously at early stage. At 24 hpf, nqo1 variant 2 was mainly expressed in yolk cells, and slightly in head and eyes. At 48 hpf, nqo1 variant 2 was restricted in lateral line neuromasts. From 72 hpf to 144 hpf, nqo1 variant 2 was mainly restricted in branchial arch, liver, swimming bladder and lateral line neuromasts, while from 124 hpf to 192 hpf, nqo1 variant 2 only restricted in liver, and disappeared in lateral line neuromasts. On the contrary, at the late embryonic stage, nqo1 variant 1 was only expressed in liver and swimming bladder while not in branchial arch and lateral line neuromasts. In conclusion, we systematically analyzed the expression pattern of nqo1 variant 1 and variant 2 in zebrafish at different embryonic stages, and our data implied the possible role of nqo1 in regulating liver, branchial arch and lateral neuromasts development.

Covalent-Assembly Based Fluorescent Probes for Detection of hNQO1 and Imaging in Living Cells

Human NAD(P)H: quinone oxidoreductase (hNQO1) is an important biomarker for human malignant tumors. Detection of NQO1 accurately is of great significance to improve the early diagnosis of cancer and prognosis of cancer patients. In this study, based on the covalent assembly strategy, hNQO1-activated fluorescent probes 1 and 2 are constructed by introducing coumarin precursor 2-cyano-3-(4-(diethylamino)-2-hydroxyphenyl) acrylic acid and self-immolative linkers. Under reaction with hNQO1 and NADH, turn-on fluorescence appears due to in-situ formation of the organic fluorescent compound 7-diethylamino-3-cyanocoumarin, and fluorescent intensity changes significantly. Probe 1 and 2 for detection of hNQO1 are not interfered by other substances and have low toxicity in cells. In addition to quantitative detection of hNQO1 in vitro, they have also been successfully applied to fluorescent imaging in living cells.